1
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Satake H, Sasakura Y. The neuroendocrine system of Ciona intestinalis Type A, a deuterostome invertebrate and the closest relative of vertebrates. Mol Cell Endocrinol 2024; 582:112122. [PMID: 38109989 DOI: 10.1016/j.mce.2023.112122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 12/05/2023] [Accepted: 12/09/2023] [Indexed: 12/20/2023]
Abstract
Deuterostome invertebrates, including echinoderms, hemichordates, cephalochordates, and urochordates, exhibit common and species-specific morphological, developmental, physiological, and behavioral characteristics that are regulated by neuroendocrine and nervous systems. Over the past 15 years, omics, genetic, and/or physiological studies on deuterostome invertebrates have identified low-molecular-weight transmitters, neuropeptides and their cognate receptors, and have clarified their various biological functions. In particular, there has been increasing interest on the neuroendocrine and nervous systems of Ciona intestinalis Type A, which belongs to the subphylum Urochordata and occupies the critical phylogenetic position as the closest relative of vertebrates. During the developmental stage, gamma-aminobutylic acid, D-serine, and gonadotropin-releasing hormones regulate metamorphosis of Ciona. In adults, the neuropeptidergic mechanisms underlying ovarian follicle growth, oocyte maturation, and ovulation have been elucidated. This review article provides the most recent and fundamental knowledge of the neuroendocrine and nervous systems of Ciona, and their evolutionary aspects.
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Affiliation(s)
- Honoo Satake
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, Japan.
| | - Yasunori Sasakura
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka, Japan
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2
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Improved Genome Editing in the Ascidian Ciona with CRISPR/Cas9 and TALEN. Methods Mol Biol 2023; 2637:375-388. [PMID: 36773161 DOI: 10.1007/978-1-0716-3016-7_28] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
The ascidian Ciona intestinalis type A (or Ciona robusta) is an important organism for elucidating the mechanisms that make the chordate body plan. CRISPR/Cas9 and TAL effector nuclease (TALEN) are widely used to quickly address genetic functions in Ciona. Our previously reported method of CRISPR/Cas9-mediated mutagenesis in this animal has inferior mutation rates compared to those of TALENs. We here describe an updated way to effectively mutate genes with CRISPR/Cas9 in Ciona. Although the construction of TALENs is much more laborious than that of CRISPR/Cas9, this technique is useful for tissue-specific knockouts that are not easy even by the optimized CRISPR/Cas9 method.
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3
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Hozumi A, Matsunobu S, Mita K, Treen N, Sugihara T, Horie T, Sakuma T, Yamamoto T, Shiraishi A, Hamada M, Satoh N, Sakurai K, Satake H, Sasakura Y. GABA-Induced GnRH Release Triggers Chordate Metamorphosis. Curr Biol 2020; 30:1555-1561.e4. [PMID: 32220316 DOI: 10.1016/j.cub.2020.02.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 12/14/2019] [Accepted: 02/03/2020] [Indexed: 01/13/2023]
Abstract
Metamorphosis, a widespread life history strategy in metazoans, allows dispersal and use of different ecological niches through a dramatic body change from a larval stage [1, 2]. Despite its conservation and importance, the molecular mechanisms underlying its initiation and progression have been characterized in only a few animal models. In this study, through pharmacological and gene functional analyses, we identified neurotransmitters responsible for metamorphosis of the ascidian Ciona. Ciona metamorphosis converts swimming tadpole larvae into vase-like, sessile adults. Here, we show that the neurotransmitter GABA is a key regulator of metamorphosis. We found that gonadotropin-releasing hormone (GnRH) is a downstream neuropeptide of GABA. Although GABA is generally thought of as an inhibitory neurotransmitter, we found that it positively regulates secretion of GnRH through the metabotropic GABA receptor during Ciona metamorphosis. GnRH is necessary for reproductive maturation in vertebrates, and GABA is an important excitatory regulator of GnRH in the hypothalamus during puberty [3, 4]. Our findings reveal another role of the GABA-GnRH axis in the regulation of post-embryonic development in chordates.
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Affiliation(s)
- Akiko Hozumi
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka 415-0025, Japan
| | - Shohei Matsunobu
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka 415-0025, Japan
| | - Kaoru Mita
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka 415-0025, Japan
| | - Nicholas Treen
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka 415-0025, Japan
| | - Takaho Sugihara
- Department of Biology, Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8572, Japan
| | - Takeo Horie
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka 415-0025, Japan
| | - Tetsushi Sakuma
- Division of Integrated Sciences for Life, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima 739-8526, Japan
| | - Takashi Yamamoto
- Division of Integrated Sciences for Life, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima 739-8526, Japan
| | - Akira Shiraishi
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto 619-0284, Japan
| | - Mayuko Hamada
- Ushimado Marine Institute, Okayama University, Okayama 701-4303, Japan
| | - Noriyuki Satoh
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa 904-0495, Japan
| | - Keisuke Sakurai
- Department of Biology, Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8572, Japan
| | - Honoo Satake
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto 619-0284, Japan
| | - Yasunori Sasakura
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka 415-0025, Japan.
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4
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Sawada H, Yamamoto K, Yamaguchi A, Yamada L, Higuchi A, Nukaya H, Fukuoka M, Sakuma T, Yamamoto T, Sasakura Y, Shirae-Kurabayashi M. Three multi-allelic gene pairs are responsible for self-sterility in the ascidian Ciona intestinalis. Sci Rep 2020; 10:2514. [PMID: 32054881 PMCID: PMC7018956 DOI: 10.1038/s41598-020-59147-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 01/13/2020] [Indexed: 12/13/2022] Open
Abstract
Many hermaphroditic organisms possess a self-incompatibility system to avoid inbreeding. Although the mechanisms of self-incompatibility in flowering plants are well known, little is known about the mechanisms of self-sterility in hermaphroditic marine invertebrates. Ascidians are hermaphroditic sessile marine invertebrates that release sperm and eggs into the surrounding seawater. Several species, including Ciona intestinalis type A (Ciona robusta), exhibit strict self-sterility. In a previous study, we found that the candidate genes responsible for self-sterility in Ciona reside in chromosome 2q (locus A) and chromosome 7q (locus B). Two pairs of multi-allelic genes, named s(sperm)-Themis-A and v(vitelline-coat)-Themis-A in locus A and s-Themis-B and v-Themis-B in locus B, are responsible for self-sterility. In this study, we identified a third multi-allelic gene pair, s-Themis-B2 and v-Themis-B2, within locus B that is also involved in this system. Genetic analysis revealed that the haplotypes of s/v-Themis-A, s/v-Themis-B and s/v-Themis-B2 play essential roles in self-sterility. When three haplotypes were matched between s-Themis and v-Themis, fertilization never occurred even in nonself crossing. Interestingly, gene targeting of either s/v-Themis-B/B2 or s/v-Themis-A by genome editing enabled self-fertilization. These results indicate that s/v-Themis-A, -B and -B2 are S-determinant genes responsible for self-sterility in the ascidian C. intestinalis type A.
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Affiliation(s)
- Hitoshi Sawada
- Sugashima Marine Biological Laboratory, Graduate School of Science, Nagoya University, Sugashima, Toba, 517-0004, Japan.
| | - Kazunori Yamamoto
- Sugashima Marine Biological Laboratory, Graduate School of Science, Nagoya University, Sugashima, Toba, 517-0004, Japan
| | - Akira Yamaguchi
- Sugashima Marine Biological Laboratory, Graduate School of Science, Nagoya University, Sugashima, Toba, 517-0004, Japan
| | - Lixy Yamada
- Sugashima Marine Biological Laboratory, Graduate School of Science, Nagoya University, Sugashima, Toba, 517-0004, Japan
| | - Arata Higuchi
- Sugashima Marine Biological Laboratory, Graduate School of Science, Nagoya University, Sugashima, Toba, 517-0004, Japan
| | - Haruhiko Nukaya
- Sugashima Marine Biological Laboratory, Graduate School of Science, Nagoya University, Sugashima, Toba, 517-0004, Japan
| | - Masashi Fukuoka
- Sugashima Marine Biological Laboratory, Graduate School of Science, Nagoya University, Sugashima, Toba, 517-0004, Japan
| | - Tetsushi Sakuma
- Division of Integrated Sciences for Life, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, 739-8526, Japan
| | - Takashi Yamamoto
- Division of Integrated Sciences for Life, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, 739-8526, Japan
| | - Yasunori Sasakura
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka, 415-0025, Japan
| | - Maki Shirae-Kurabayashi
- Sugashima Marine Biological Laboratory, Graduate School of Science, Nagoya University, Sugashima, Toba, 517-0004, Japan
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Tajima Y, Hozumi A, Yoshida K, Treen N, Sakuma T, Yamamoto T, Sasakura Y. Hox13 is essential for formation of a sensory organ at the terminal end of the sperm duct in Ciona. Dev Biol 2019; 458:120-131. [PMID: 31682808 DOI: 10.1016/j.ydbio.2019.10.028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 10/29/2019] [Accepted: 10/29/2019] [Indexed: 02/06/2023]
Abstract
Species-specific traits are thought to have been acquired by natural selection. Transcription factors play central roles in the evolution of species-specific traits. Hox genes encode a set of conserved transcription factors essential for establishing the anterior-posterior body axis of animals. Changes in the expression or function of Hox genes can lead to the diversification of animal-body plans. The tunicate ascidian Ciona intestinalis Type A has an orange-colored structure at the sperm duct terminus. This orange-pigmented organ (OPO) is the characteristic that can distinguish this ascidian from other closely related species. The OPO is formed by the accumulation of orange-pigmented cells (OPCs) that are present throughout the adult body. We show that Hox13 is essential for formation of the OPO. Hox13 is expressed in the epithelium of the sperm duct and neurons surrounding the terminal openings for sperm ejection, while OPCs themselves do not express this gene. OPCs are mobile cells that can move through the body vasculature by pseudopodia, suggesting that the OPO is formed by the accumulation of OPCs guided by Hox13-positive cells. Another ascidian species, Ciona savignyi, does not have an OPO. Like Hox13 of C. intestinalis, Hox13 of C. savignyi is expressed at the terminus of its sperm duct; however, its expression domain is limited to the circular area around the openings. The genetic changes responsible for the acquisition or loss of OPO are likely to occur in the expression pattern of Hox13.
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Affiliation(s)
- Yukako Tajima
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka, 415-0025, Japan
| | - Akiko Hozumi
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka, 415-0025, Japan
| | - Keita Yoshida
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka, 415-0025, Japan
| | - Nicholas Treen
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka, 415-0025, Japan
| | - Tetsushi Sakuma
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Hiroshima, Japan
| | - Takashi Yamamoto
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Hiroshima, Japan
| | - Yasunori Sasakura
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka, 415-0025, Japan.
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6
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Gandhi S, Razy-Krajka F, Christiaen L, Stolfi A. CRISPR Knockouts in Ciona Embryos. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1029:141-152. [PMID: 29542087 PMCID: PMC6061950 DOI: 10.1007/978-981-10-7545-2_13] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 has emerged as a revolutionary tool for fast and efficient targeted gene knockouts and genome editing in almost any organism. The laboratory model tunicate Ciona is no exception. Here, we describe our latest protocol for the design, implementation, and evaluation of successful CRISPR/Cas9-mediated gene knockouts in somatic cells of electroporated Ciona embryos. Using commercially available reagents, publicly accessible plasmids, and free web-based software applications, any Ciona researcher can easily knock out any gene of interest in their favorite embryonic cell lineage.
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Affiliation(s)
- Shashank Gandhi
- Center for Developmental Genetics, Department of Biology, New York University, New York, NY, USA
| | - Florian Razy-Krajka
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Lionel Christiaen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.
| | - Alberto Stolfi
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
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Abstract
Targeted mutagenesis of genes-of-interest is a powerful method of addressing the functions of genes. Genome editing techniques, such as transcriptional activator-like effector nucleases (TALENs) and clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 systems, have enabled this approach in various organisms because of their ease of use. In the ascidian, Ciona intestinalis, recent studies show that TALEN-based knockout can be applied to establishing both mutant lines and tissue-specific knockout for addressing gene functions. Here, we introduce recent updates to the TALEN toolkit that facilitate detailed functional analysis of genes in ascidians.
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Transgenic Techniques for Investigating Cell Biology During Development. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018. [PMID: 29542088 DOI: 10.1007/978-981-10-7545-2_14] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Ascidians are increasingly being used as a system for investigating cell biology during development. The extreme genetic and cellular simplicity of ascidian embryos in combination with superior experimental tractability make this an ideal system for in vivo analysis of dynamic cellular processes. Transgenic approaches to cellular and sub-cellular analysis of ascidian development have begun to yield new insights into the mechanisms regulating developmental signaling and morphogenesis. This chapter focuses on the targeted expression of fusion proteins in ascidian embryos and how this technique is being deployed to garner new insights into the cell biology of development.
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9
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Knowlton MN, Smith CL. Naming CRISPR alleles: endonuclease-mediated mutation nomenclature across species. Mamm Genome 2017; 28:367-376. [PMID: 28589392 PMCID: PMC5569137 DOI: 10.1007/s00335-017-9698-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Accepted: 05/27/2017] [Indexed: 12/29/2022]
Abstract
The widespread use of CRISPR/Cas and other targeted endonuclease technologies in many species has led to an explosion in the generation of new mutations and alleles. The ability to generate many different mutations from the same target sequence either by homology-directed repair with a donor sequence or non-homologous end joining-induced insertions and deletions necessitates a means for representing these mutations in literature and databases. Standardized nomenclature can be used to generate unambiguous, concise, and specific symbols to represent mutations and alleles. The research communities of a variety of species using CRISPR/Cas and other endonuclease-mediated mutation technologies have developed different approaches to naming and identifying such alleles and mutations. While some organism-specific research communities have developed allele nomenclature that incorporates the method of generation within the official allele or mutant symbol, others use metadata tags that include method of generation or mutagen. Organism-specific research community databases together with organism-specific nomenclature committees are leading the way in providing standardized nomenclature and metadata to facilitate the integration of data from alleles and mutations generated using CRISPR/Cas and other targeted endonucleases.
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Affiliation(s)
| | - Cynthia L Smith
- Mouse Genome Informatics, The Jackson Laboratory, Bar Harbor, 04609, USA
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10
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Gandhi S, Haeussler M, Razy-Krajka F, Christiaen L, Stolfi A. Evaluation and rational design of guide RNAs for efficient CRISPR/Cas9-mediated mutagenesis in Ciona. Dev Biol 2017; 425:8-20. [PMID: 28341547 PMCID: PMC5502750 DOI: 10.1016/j.ydbio.2017.03.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 02/06/2017] [Accepted: 03/05/2017] [Indexed: 12/26/2022]
Abstract
The CRISPR/Cas9 system has emerged as an important tool for various genome engineering applications. A current obstacle to high throughput applications of CRISPR/Cas9 is the imprecise prediction of highly active single guide RNAs (sgRNAs). We previously implemented the CRISPR/Cas9 system to induce tissue-specific mutations in the tunicate Ciona. In the present study, we designed and tested 83 single guide RNA (sgRNA) vectors targeting 23 genes expressed in the cardiopharyngeal progenitors and surrounding tissues of Ciona embryo. Using high-throughput sequencing of mutagenized alleles, we identified guide sequences that correlate with sgRNA mutagenesis activity and used this information for the rational design of all possible sgRNAs targeting the Ciona transcriptome. We also describe a one-step cloning-free protocol for the assembly of sgRNA expression cassettes. These cassettes can be directly electroporated as unpurified PCR products into Ciona embryos for sgRNA expression in vivo, resulting in high frequency of CRISPR/Cas9-mediated mutagenesis in somatic cells of electroporated embryos. We found a strong correlation between the frequency of an Ebf loss-of-function phenotype and the mutagenesis efficacies of individual Ebf-targeting sgRNAs tested using this method. We anticipate that our approach can be scaled up to systematically design and deliver highly efficient sgRNAs for the tissue-specific investigation of gene functions in Ciona.
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Affiliation(s)
| | - Maximilian Haeussler
- Santa Cruz Genomics Institute, University of California, MS CBSE, Santa Cruz, USA
| | | | | | - Alberto Stolfi
- Department of Biology, New York University, New York, USA.
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11
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Germ cell regeneration-mediated, enhanced mutagenesis in the ascidian Ciona intestinalis reveals flexible germ cell formation from different somatic cells. Dev Biol 2017; 423:111-125. [DOI: 10.1016/j.ydbio.2017.01.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 01/12/2017] [Accepted: 01/31/2017] [Indexed: 11/22/2022]
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Abstract
The ascidian Ciona intestinalis is an important model animal for studying developmental mechanisms for constructing the chordate body. Although molecular and embryological techniques for manipulating Ciona genes were developed a long time ago, recent achievements of genome editing in this animal have innovated functional analyses of genes in Ciona. Particularly, knockout of genes in the G0 generation coupled with tissue-specific expression of TALENs enables us to rapidly address gene functions that were difficult using previous methods.
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Affiliation(s)
- Yasunori Sasakura
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1, Shimoda, Shizuoka, 415-0025, Japan.
| | - Keita Yoshida
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1, Shimoda, Shizuoka, 415-0025, Japan
| | - Nicholas Treen
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1, Shimoda, Shizuoka, 415-0025, Japan
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13
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Diving into marine genomics with CRISPR/Cas9 systems. Mar Genomics 2016; 30:55-65. [DOI: 10.1016/j.margen.2016.10.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 10/03/2016] [Accepted: 10/03/2016] [Indexed: 12/12/2022]
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14
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Ueki T, Yamaguchi N, Romaidi, Isago Y, Tanahashi H. Vanadium accumulation in ascidians: A system overview. Coord Chem Rev 2015. [DOI: 10.1016/j.ccr.2014.09.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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15
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Aluru N, Karchner SI, Franks DG, Nacci D, Champlin D, Hahn ME. Targeted mutagenesis of aryl hydrocarbon receptor 2a and 2b genes in Atlantic killifish (Fundulus heteroclitus). AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2015; 158:192-201. [PMID: 25481785 PMCID: PMC4272816 DOI: 10.1016/j.aquatox.2014.11.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 11/17/2014] [Accepted: 11/18/2014] [Indexed: 06/04/2023]
Abstract
Understanding molecular mechanisms of toxicity is facilitated by experimental manipulations, such as disruption of function by gene targeting, that are especially challenging in non-standard model species with limited genomic resources. While loss-of-function approaches have included gene knock-down using morpholino-modified oligonucleotides and random mutagenesis using mutagens or retroviruses, more recent approaches include targeted mutagenesis using zinc finger nuclease (ZFN), transcription activator-like effector nuclease (TALENs) and clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 technology. These latter methods provide more accessible opportunities to explore gene function in non-traditional model species. To facilitate evaluation of toxic mechanisms for important categories of aryl hydrocarbon pollutants, whose actions are known to be receptor mediated, we used ZFN and CRISPR-Cas9 approaches to generate aryl hydrocarbon receptor 2a (AHR2a) and AHR2b gene mutations in Atlantic killifish (Fundulus heteroclitus) embryos. This killifish is a particularly valuable non-traditional model, with multiple paralogs of AHR whose functions are not well characterized. In addition, some populations of this species have evolved resistance to toxicants such as halogenated aromatic hydrocarbons. AHR-null killifish will be valuable for characterizing the role of the individual AHR paralogs in evolved resistance, as well as in normal development. We first used five-finger ZFNs targeting exons 1 and 3 of AHR2a. Subsequently, CRISPR-Cas9 guide RNAs were designed to target regions in exon 2 and 3 of AHR2a and AHR2b. We successfully induced frameshift mutations in AHR2a exon 3 with ZFN and CRISPR-Cas9 guide RNAs, with mutation frequencies of 10% and 16%, respectively. In AHR2b, mutations were induced using CRISPR-Cas9 guide RNAs targeting sites in both exon 2 (17%) and exon 3 (63%). We screened AHR2b exon 2 CRISPR-Cas9-injected embryos for off-target effects in AHR paralogs. No mutations were observed in closely related AHR genes (AHR1a, AHR1b, AHR2a, AHRR) in the CRISPR-Cas9-injected embryos. Overall, our results demonstrate that targeted genome-editing methods are efficient in inducing mutations at specific loci in embryos of a non-traditional model species, without detectable off-target effects in paralogous genes.
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Affiliation(s)
- Neelakanteswar Aluru
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA; Superfund Research Program, Boston University School of Public Health, Boston, MA, USA.
| | - Sibel I Karchner
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA; Superfund Research Program, Boston University School of Public Health, Boston, MA, USA
| | - Diana G Franks
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA; Superfund Research Program, Boston University School of Public Health, Boston, MA, USA
| | - Diane Nacci
- Office of Research and Development, National Health and Environmental Effects Research Laboratory, Atlantic Ecology Division, Environmental Protection Agency, Narragansett, RI 02882, USA
| | - Denise Champlin
- Office of Research and Development, National Health and Environmental Effects Research Laboratory, Atlantic Ecology Division, Environmental Protection Agency, Narragansett, RI 02882, USA
| | - Mark E Hahn
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA; Superfund Research Program, Boston University School of Public Health, Boston, MA, USA
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16
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Stolfi A, Gandhi S, Salek F, Christiaen L. Tissue-specific genome editing in Ciona embryos by CRISPR/Cas9. Development 2014; 141:4115-20. [PMID: 25336740 DOI: 10.1242/dev.114488] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The CRISPR/Cas9 system has ushered in a new era of targeted genetic manipulations. Here, we report the use of CRISPR/Cas9 to induce double-stranded breaks in the genome of the sea squirt Ciona intestinalis. We use electroporation to deliver CRISPR/Cas9 components for tissue-specific disruption of the Ebf (Collier/Olf/EBF) gene in hundreds of synchronized Ciona embryos. Phenotyping of transfected embryos in the 'F0' generation revealed that endogenous Ebf function is required for specification of Islet-expressing motor ganglion neurons and atrial siphon muscles. We demonstrate that CRISPR/Cas9 is sufficiently effective and specific to generate large numbers of embryos carrying mutations in a targeted gene of interest, which should allow for rapid screening of gene function in Ciona.
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Affiliation(s)
- Alberto Stolfi
- Center for Developmental Genetics, Department of Biology, New York University, New York, NY 10003, USA
| | - Shashank Gandhi
- Center for Developmental Genetics, Department of Biology, New York University, New York, NY 10003, USA
| | - Farhana Salek
- Center for Developmental Genetics, Department of Biology, New York University, New York, NY 10003, USA
| | - Lionel Christiaen
- Center for Developmental Genetics, Department of Biology, New York University, New York, NY 10003, USA
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17
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Crocetta F, Marino R, Cirino P, Macina A, Staiano L, Esposito R, Pezzotti MR, Racioppi C, Toscano F, De Felice E, Locascio A, Ristoratore F, Spagnuolo A, Zanetti L, Branno M, Sordino P. Mutation studies in ascidians: a review. Genesis 2014; 53:160-9. [PMID: 25395385 DOI: 10.1002/dvg.22837] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 11/06/2014] [Accepted: 11/11/2014] [Indexed: 12/21/2022]
Abstract
Historically, mutations have had a significant impact on the study of developmental processes and phenotypic evolution. Lesions in DNA are created by artificial methods or detected by natural genetic variation. Random mutations are then ascribed to genetic change by direct sequencing or positional cloning. Tunicate species of the ascidian genus Ciona represent nearly fully realized model systems in which gene function can be investigated in depth. Additionally, tunicates are valuable organisms for the study of naturally occurring mutations due to the capability to exploit genetic variation down to the molecular level. Here, we summarize the available information about how mutations are studied in ascidians with examples of insights that have resulted from these applications. We also describe notions and methodologies that might be useful for the implementation of easy and tight procedures for mutations studies in Ciona.
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Affiliation(s)
- Fabio Crocetta
- Laboratory of Cellular and Developmental Biology, Stazione Zoologica Anton Dohrn, Villa Comunale, Naples, Italy
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18
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Kawaguchi A, Utsumi N, Morita M, Ohya A, Wada S. Application of thecis-regulatory region of a heat-shock protein 70 gene to heat-inducible gene expression in the ascidianCiona intestinalis. Genesis 2014; 53:170-82. [PMID: 25366274 DOI: 10.1002/dvg.22834] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 10/28/2014] [Accepted: 10/29/2014] [Indexed: 11/11/2022]
Affiliation(s)
- Akane Kawaguchi
- Department of Bioscience; Faculty of Bioscience; Nagahama Institute of Bio-Science and Technology; Nagahama Shiga Japan
| | - Nanami Utsumi
- Department of Animal Bioscience; Faculty of Bioscience; Nagahama Institute of Bio-Science and Technology; Nagahama Shiga Japan
| | - Maki Morita
- Guraduate School of Bioscience; Nagahama Institute of Bio-Science and Technology; Nagahama Shiga Japan
| | - Aya Ohya
- Department of Bioscience; Faculty of Bioscience; Nagahama Institute of Bio-Science and Technology; Nagahama Shiga Japan
| | - Shuichi Wada
- Department of Animal Bioscience; Faculty of Bioscience; Nagahama Institute of Bio-Science and Technology; Nagahama Shiga Japan
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19
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Sasaki H, Yoshida K, Hozumi A, Sasakura Y. CRISPR/Cas9-mediated gene knockout in the ascidian Ciona intestinalis. Dev Growth Differ 2014; 56:499-510. [PMID: 25212715 PMCID: PMC4231237 DOI: 10.1111/dgd.12149] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 06/18/2014] [Accepted: 06/22/2014] [Indexed: 01/25/2023]
Abstract
Knockout of genes with CRISPR/Cas9 is a newly emerged approach to investigate functions of genes in various organisms. We demonstrate that CRISPR/Cas9 can mutate endogenous genes of the ascidian Ciona intestinalis, a splendid model for elucidating molecular mechanisms for constructing the chordate body plan. Short guide RNA (sgRNA) and Cas9 mRNA, when they are expressed in Ciona embryos by means of microinjection or electroporation of their expression vectors, introduced mutations in the target genes. The specificity of target choice by sgRNA is relatively high compared to the reports from some other organisms, and a single nucleotide mutation at the sgRNA dramatically reduced mutation efficiency at the on-target site. CRISPR/Cas9-mediated mutagenesis will be a powerful method to study gene functions in Ciona along with another genome editing approach using TALE nucleases.
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Affiliation(s)
- Haruka Sasaki
- Shimoda Marine Research Center, University of TsukubaShimoda, Shizuoka, 415-0025, Japan
| | - Keita Yoshida
- Shimoda Marine Research Center, University of TsukubaShimoda, Shizuoka, 415-0025, Japan
| | - Akiko Hozumi
- Shimoda Marine Research Center, University of TsukubaShimoda, Shizuoka, 415-0025, Japan
| | - Yasunori Sasakura
- Shimoda Marine Research Center, University of TsukubaShimoda, Shizuoka, 415-0025, Japan
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20
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Iitsuka T, Mita K, Hozumi A, Hamada M, Satoh N, Sasakura Y. Transposon-mediated targeted and specific knockdown of maternally expressed transcripts in the ascidian Ciona intestinalis. Sci Rep 2014; 4:5050. [PMID: 24854849 PMCID: PMC4031475 DOI: 10.1038/srep05050] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Accepted: 05/06/2014] [Indexed: 12/05/2022] Open
Abstract
Maternal mRNAs play crucial roles during early embryogenesis of ascidians, but their functions are largely unknown. In this study, we developed a new method to specifically knockdown maternal mRNAs in Ciona intestinalis using transposon-mediated transgenesis. We found that GFP expression is epigenetically silenced in Ciona intestinalis oocytes and eggs, and this epigenetic silencing of GFP was used to develop the knockdown method. When the 5' upstream promoter and 5' untranslated region (UTR) of a maternal gene are used to drive GFP in eggs, the maternal gene is specifically knocked down together with GFP. The 5' UTR of the maternal gene is the major element that determines the target gene silencing. Zygotic transcription of the target gene is unaffected, suggesting that the observed phenotypes specifically reflect the maternal function of the gene. This new method can provide breakthroughs in studying the functions of maternal mRNAs.
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Affiliation(s)
- Takako Iitsuka
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka 415-0025, Japan
| | - Kaoru Mita
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka 415-0025, Japan
| | - Akiko Hozumi
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka 415-0025, Japan
| | - Mayuko Hamada
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
| | - Nori Satoh
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
| | - Yasunori Sasakura
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka 415-0025, Japan
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21
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Yoshida K, Treen N, Hozumi A, Sakuma T, Yamamoto T, Sasakura Y. Germ cell mutations of the ascidianCiona intestinaliswith TALE nucleases. Genesis 2014; 52:431-9. [DOI: 10.1002/dvg.22770] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 03/05/2014] [Accepted: 03/06/2014] [Indexed: 11/07/2022]
Affiliation(s)
- Keita Yoshida
- Shimoda Marine Research Center; University of Tsukuba; Shimoda Shizuoka 415-0025 Japan
| | - Nicholas Treen
- Shimoda Marine Research Center; University of Tsukuba; Shimoda Shizuoka 415-0025 Japan
| | - Akiko Hozumi
- Shimoda Marine Research Center; University of Tsukuba; Shimoda Shizuoka 415-0025 Japan
| | - Tetsushi Sakuma
- Department of Mathematical and Life Sciences, Graduate School of Science; Hiroshima University; 1-3-1 Kagamiyama Higashi-Hiroshima Hiroshima 739-8526 Japan
| | - Takashi Yamamoto
- Department of Mathematical and Life Sciences, Graduate School of Science; Hiroshima University; 1-3-1 Kagamiyama Higashi-Hiroshima Hiroshima 739-8526 Japan
| | - Yasunori Sasakura
- Shimoda Marine Research Center; University of Tsukuba; Shimoda Shizuoka 415-0025 Japan
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22
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Abstract
Current technology enables the production of highly specific genome modifications with excellent efficiency and specificity. Key to this capability are targetable DNA cleavage reagents and cellular DNA repair pathways. The break made by these reagents can produce localized sequence changes through inaccurate nonhomologous end joining (NHEJ), often leading to gene inactivation. Alternatively, user-provided DNA can be used as a template for repair by homologous recombination (HR), leading to the introduction of desired sequence changes. This review describes three classes of targetable cleavage reagents: zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and CRISPR/Cas RNA-guided nucleases (RGNs). As a group, these reagents have been successfully used to modify genomic sequences in a wide variety of cells and organisms, including humans. This review discusses the properties, advantages, and limitations of each system, as well as the specific considerations required for their use in different biological systems.
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Affiliation(s)
- Dana Carroll
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112;
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23
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Ishii H, Shirai T, Makino C, Nishikata T. Mitochondrial inhibitor sodium azide inhibits the reorganization of mitochondria-rich cytoplasm and the establishment of the anteroposterior axis in ascidian embryo. Dev Growth Differ 2014; 56:175-88. [DOI: 10.1111/dgd.12117] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 12/04/2013] [Accepted: 12/04/2013] [Indexed: 11/30/2022]
Affiliation(s)
- Hirokazu Ishii
- Frontiers of Innovative Research in Science and Technology (FIRST); Konan University; Kobe Hyogo 650-0047 Japan
| | - Takuma Shirai
- Frontiers of Innovative Research in Science and Technology (FIRST); Konan University; Kobe Hyogo 650-0047 Japan
| | - Chisato Makino
- Frontiers of Innovative Research in Science and Technology (FIRST); Konan University; Kobe Hyogo 650-0047 Japan
| | - Takahito Nishikata
- Frontiers of Innovative Research in Science and Technology (FIRST); Konan University; Kobe Hyogo 650-0047 Japan
- Frontier Institute for Biomolecular Engineering Research (FIBER); Konan University; Kobe Hyogo 650-0047 Japan
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24
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Sakuma T, Woltjen K. Nuclease-mediated genome editing: At the front-line of functional genomics technology. Dev Growth Differ 2014; 56:2-13. [PMID: 24387662 DOI: 10.1111/dgd.12111] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 11/18/2013] [Accepted: 11/18/2013] [Indexed: 12/26/2022]
Abstract
Genome editing with engineered endonucleases is rapidly becoming a staple method in developmental biology studies. Engineered nucleases permit random or designed genomic modification at precise loci through the stimulation of endogenous double-strand break repair. Homology-directed repair following targeted DNA damage is mediated by co-introduction of a custom repair template, allowing the derivation of knock-out and knock-in alleles in animal models previously refractory to classic gene targeting procedures. Currently there are three main types of customizable site-specific nucleases delineated by the source mechanism of DNA binding that guides nuclease activity to a genomic target: zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and clustered regularly interspaced short palindromic repeats (CRISPR). Among these genome engineering tools, characteristics such as the ease of design and construction, mechanism of inducing DNA damage, and DNA sequence specificity all differ, making their application complementary. By understanding the advantages and disadvantages of each method, one may make the best choice for their particular purpose.
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Affiliation(s)
- Tetsushi Sakuma
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
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25
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Treen N, Yoshida K, Sakuma T, Sasaki H, Kawai N, Yamamoto T, Sasakura Y. Tissue-specific and ubiquitous gene knockouts by TALEN electroporation provide new approaches to investigating gene function in Ciona. Development 2013; 141:481-7. [PMID: 24353063 DOI: 10.1242/dev.099572] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Custom designed nucleases can simplify gene targeting experiments and have the potential to allow these techniques to be performed in a wide range of organisms. Transcriptional activator-like effector nucleases (TALENs) are starting to fulfill this potential with the advantages of low cost and fast construction times. Here, we report that TALENs are highly effective at inducing mutations in specific genomic loci in the ascidian chordate Ciona intestinalis. In Ciona there are well-established methods to introduce exogenous DNA by electroporation, and we show that this method can be used to introduce constructs that can express TALENs ubiquitously or in specific tissues. Our current protocols enable the rapid analysis of hundreds of TALEN-induced mutants. TALEN electroporations result in a high rate of mutations. These mutations can result in gene knockouts that recapitulate previously described functions of Fgf3 and Hox12. We show that TALENs can work efficiently to cause tissue-specific knockouts and demonstrate this by knocking out Hox12 in the epidermis and Fgf3 in neural tissues. We also use tissue-specific knockouts to reveal a new function of Fgf3 during ascidian larval metamorphosis.
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Affiliation(s)
- Nicholas Treen
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka, 415-0025, Japan
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26
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Hosoi S, Sakuma T, Sakamoto N, Yamamoto T. Targeted mutagenesis in sea urchin embryos using TALENs. Dev Growth Differ 2013; 56:92-7. [DOI: 10.1111/dgd.12099] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 10/01/2013] [Accepted: 10/02/2013] [Indexed: 12/13/2022]
Affiliation(s)
- Sayaka Hosoi
- Department of Mathematical and Life Sciences; Graduate School of Science; Hiroshima University; 1-3-1 Kagamiyama Higashi-Hiroshima 739-8526 Japan
| | - Tetsushi Sakuma
- Department of Mathematical and Life Sciences; Graduate School of Science; Hiroshima University; 1-3-1 Kagamiyama Higashi-Hiroshima 739-8526 Japan
| | - Naoaki Sakamoto
- Department of Mathematical and Life Sciences; Graduate School of Science; Hiroshima University; 1-3-1 Kagamiyama Higashi-Hiroshima 739-8526 Japan
| | - Takashi Yamamoto
- Department of Mathematical and Life Sciences; Graduate School of Science; Hiroshima University; 1-3-1 Kagamiyama Higashi-Hiroshima 739-8526 Japan
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27
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Engineering nucleases for gene targeting: safety and regulatory considerations. N Biotechnol 2013; 31:18-27. [PMID: 23851284 DOI: 10.1016/j.nbt.2013.07.001] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 06/24/2013] [Accepted: 07/03/2013] [Indexed: 12/26/2022]
Abstract
Nuclease-based gene targeting (NBGT) represents a significant breakthrough in targeted genome editing since it is applicable from single-celled protozoa to human, including several species of economic importance. Along with the fast progress in NBGT and the increasing availability of customized nucleases, more data are available about off-target effects associated with the use of this approach. We discuss how NBGT may offer a new perspective for genetic modification, we address some aspects crucial for a safety improvement of the corresponding techniques and we also briefly relate the use of NBGT applications and products to the regulatory oversight.
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28
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Abstract
Genome engineering--the ability to precisely alter the DNA information in living cells--is beginning to transform human genetics and genomics. Advances in tools and methods have enabled genetic modifications ranging from the "scarless" correction of a single base pair to the deletion of entire chromosomes. Targetable nucleases are leading the advances in this field, providing the tools to modify any gene in seemingly any organism with high efficiency. Targeted gene alterations have now been reported in more than 30 diverse species, ending the reign of mice as the exclusive model of mammalian genetics, and targetable nucleases have been used to modify more than 150 human genes and loci. A nuclease has also already entered clinical trials, signaling the beginning of genome engineering as therapy. The recent dramatic increase in the number of investigators using these techniques signifies a transition away from methods development toward a new age of exciting applications.
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Affiliation(s)
- David J Segal
- Genome Center and Department of Biochemistry and Molecular Medicine, University of California, Davis, California 95616;
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29
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Sakuma T, Hosoi S, Woltjen K, Suzuki KI, Kashiwagi K, Wada H, Ochiai H, Miyamoto T, Kawai N, Sasakura Y, Matsuura S, Okada Y, Kawahara A, Hayashi S, Yamamoto T. Efficient TALEN construction and evaluation methods for human cell and animal applications. Genes Cells 2013; 18:315-26. [PMID: 23388034 DOI: 10.1111/gtc.12037] [Citation(s) in RCA: 136] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Accepted: 12/19/2012] [Indexed: 12/25/2022]
Abstract
Transcription activator-like effector nucleases (TALENs) have recently arisen as effective tools for targeted genome engineering. Here, we report streamlined methods for the construction and evaluation of TALENs based on the 'Golden Gate TALEN and TAL Effector Kit' (Addgene). We diminished array vector requirements and increased assembly rates using six-module concatemerization. We altered the architecture of the native TALEN protein to increase nuclease activity and replaced the final destination vector with a mammalian expression/in vitro transcription vector bearing both CMV and T7 promoters. Using our methods, the whole process, from initiating construction to completing evaluation directly in mammalian cells, requires only 1 week. Furthermore, TALENs constructed in this manner may be directly applied to transfection of cultured cells or mRNA synthesis for use in animals and embryos. In this article, we show genomic modification of HEK293T cells, human induced pluripotent stem cells, Drosophila melanogaster, Danio rerio and Xenopus laevis, using custom-made TALENs constructed and evaluated with our protocol. Our methods are more time efficient compared with conventional yeast-based evaluation methods and provide a more accessible and effective protocol for the application of TALENs in various model organisms.
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Affiliation(s)
- Tetsushi Sakuma
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
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30
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Enhancer activity sensitive to the orientation of the gene it regulates in the chordate genome. Dev Biol 2012; 375:79-91. [PMID: 23274690 DOI: 10.1016/j.ydbio.2012.12.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Revised: 11/22/2012] [Accepted: 12/13/2012] [Indexed: 12/26/2022]
Abstract
Enhancers are flexible in terms of their location and orientation relative to the genes they regulate. However, little is known about whether the flexibility can be applied in every combination of enhancers and genes. Enhancer detection with transposable elements is a powerful method to identify enhancers in the genome and to create marker lines expressing fluorescent proteins in a tissue-specific manner. In the chordate Ciona intestinalis, this method has been established with a Tc1/mariner superfamily transposon Minos. Previously, we created the enhancer detection line E[MiTSAdTPOG]15 (E15) that specifically expresses green fluorescent protein (GFP) in the central nervous system (CNS) after metamorphosis. In this study, we identified the causal insertion site of the transgenic line. There are two genes flanking the causal insertion of the E15 line, and the genomic region around the insertion site contains the enhancers responsible for the expression in the endostyle and gut in addition to the CNS. We found that the endostyle and gut enhancers show sensitivity to the orientation of the GFP gene for their enhancer activity. Namely, the enhancers cannot enhance the expression of GFP which is inserted at the same orientation as the E15 line, while the enhancers can enhance GFP expression inserted at the opposite orientation. The CNS enhancer can enhance GFP expression in both orientations. The DNA element adjacent to the endostyle enhancer is responsible for the orientation sensitivity of the enhancer. The different sensitivity of the enhancers to the orientation of the transgene is a cause of CNS-specific GFP expression in the E15 line.
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31
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Nakajima K, Nakajima T, Takase M, Yaoita Y. Generation of albino Xenopus tropicalis using zinc-finger nucleases. Dev Growth Differ 2012; 54:777-84. [PMID: 23106502 DOI: 10.1111/dgd.12006] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2012] [Revised: 09/07/2012] [Accepted: 09/09/2012] [Indexed: 01/23/2023]
Abstract
To generate albino lines of Xenopus tropicalis, we injected fertilized eggs with mRNAs encoding zinc-finger nucleases (ZFNs) targeting the tyrosinase coding region. Surprisingly, vitiligo was observed on the skin of F0 frogs that had been injected with ZFN mRNAs, indicating that both tyrosinase genes in the genome were disrupted in all melanocytes within the vitiligo patches. Mutation analysis using genomic DNA from the skin revealed that two mosaic F0 frogs underwent spatially complex tyrosinase gene mutations. The data implies that the ZFN-induced tyrosinase gene ablations occurred randomly over space and time throughout the entire body, possibly until the young tadpole stage, and that melanocyte precursors lacking functional tyrosinase proliferated and formed vitiligo patches. Several albino X. tropicalis, which are compound heterozygotes for biallelic tyrosinase mutations, were obtained by mating the mosaic F0 frogs. To our knowledge, this is the first report of the albino vertebrates generated by the targeted gene knockout.
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Affiliation(s)
- Keisuke Nakajima
- Division of Embryology and Genetics, Institute for Amphibian Biology, Graduate School of Science, Hiroshima University, Higashihiroshima, 739-8526, Japan
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32
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Stolfi A, Christiaen L. Genetic and genomic toolbox of the chordate Ciona intestinalis. Genetics 2012; 192:55-66. [PMID: 22964837 PMCID: PMC3430545 DOI: 10.1534/genetics.112.140590] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2012] [Accepted: 04/30/2012] [Indexed: 02/01/2023] Open
Abstract
The experimental malleability and unique phylogenetic position of the sea squirt Ciona intestinalis as part of the sister group to the vertebrates have helped establish these marine chordates as model organisms for the study of developmental genetics and evolution. Here we summarize the tools, techniques, and resources available to the Ciona geneticist, citing examples of studies that employed such strategies in the elucidation of gene function in Ciona. Genetic screens, germline transgenesis, electroporation of plasmid DNA, and microinjection of morpholinos are all routinely employed, and in the near future we expect these to be complemented by targeted mutagenesis, homologous recombination, and RNAi. The genomic resources available will continue to support the design and interpretation of genetic experiments and allow for increasingly sophisticated approaches on a high-throughput, whole-genome scale.
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Affiliation(s)
- Alberto Stolfi
- Center for Developmental Genetics, Department of Biology, New York University, New York, New York 10003, USA.
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