Breakthroughs in the generation of programmable sequence-specific nucleases (SSNs), such as zinc finger nucleases (ZFNs),TAL effector nucleases (TALENs) and the RNA-directed nuclease CRISPR-associated protein 9 (Cas9)...Breakthroughs in the generation of programmable sequence-specific nucleases (SSNs), such as zinc finger nucleases (ZFNs),TAL effector nucleases (TALENs) and the RNA-directed nuclease CRISPR-associated protein 9 (Cas9), have greatly increased the ease of plant genome engineering (Voytas, 2013; Malzahn et al.,2017). Programmable SSNs introduce a DNA double-strand break展开更多
Pigs are an important resource in agriculture and serve as a model for human diseases. Due to their physiological and anatomical similarities with humans, pigs can recapitulate symptoms of human diseases, making them ...Pigs are an important resource in agriculture and serve as a model for human diseases. Due to their physiological and anatomical similarities with humans, pigs can recapitulate symptoms of human diseases, making them a useful model in biomedicine. However, in the past pig models have not been widely used partially because of the difficulty in genetic modification. The lack of true embryonic stem cells in pigs forced researchers to utilize genetic modification in somatic cells and somatic cell nuclear transfer(SCNT) to generate genetically engineered(GE) pigs carrying site-specific modifications. Although possible, this approach is extremely inefficient and GE pigs born through this method often presented developmental defects associated with the cloning process. Advancement in the gene-editing systems such as Zinc-Finger Nucleases(ZFNs), Transcription activator-like effector nucleases(TALENs), and the Clustered regularly interspaced short palindromic repeat(CRISPR)/CRISPR-associated 9(Cas9) system have dramatically increased the efficiency of producing GE pigs. These gene-editing systems, specifically engineered endonucleases, are based on inducing double-stranded breaks(DSBs) at a specific location, and then site-specific modifications can be introduced through one of the two DNA repair pathways: non-homologous end joining(NHEJ) or homology direct repair(HDR).Random insertions or deletions(indels) can be introduced through NHEJ and specific nucleotide sequences can be introduced through HDR, if donor DNA is provided. Use of these engineered endonucleases provides a higher success in genetic modifications, multiallelic modification of the genome, and an opportunity to introduce site-specific modifications during embryogenesis, thus bypassing the need of SCNT in GE pig production. This review will provide a historical prospective of GE pig production and examples of how the gene-editing system, led by engineered endonucleases, have improved GE pig production. We wil also present some of our current progress relate展开更多
Zebrafish（Danio rerio） is a well-established vertebrate animal model.A comprehensive collection of reverse genetics tools has been developed for studying gene function in this useful organism.Morpholino is the most ...Zebrafish（Danio rerio） is a well-established vertebrate animal model.A comprehensive collection of reverse genetics tools has been developed for studying gene function in this useful organism.Morpholino is the most widely used reagent to knock down target gene expression post-transcriptionally.For a long time,targeted genome modification has been heavily relied on large-scale traditional forward genetic screens,such as ENU（N-ethyl-N-nitrosourea） mutagenesis derived TILLING（Targeting Induced Local Lesions IN Genomes） strategy and pseudo-typed retrovirus mediated insertional mutagenesis.Recently,engineered endonucleases,including ZFNs（zinc finger nucleases） and TALENs（transcription activator-like effector nucleases）,provide new and efficient strategies to directly generate site-specific indel mutations by inducing double strand breaks in target genes.Here we summarize the major reverse genetic approaches for loss-of-function studies used and emerging in zebrafish,including strategies based on genome-wide mutagenesis and methods for site-specific gene targeting.Future directions and expectations will also be discussed.展开更多
In recent decades,gene-editing technologies,typically based on deoxyribonucleases to specifically modify genomic sequences,have dramatically remodeled various aspects of life sciences,including fundamental research,br...In recent decades,gene-editing technologies,typically based on deoxyribonucleases to specifically modify genomic sequences,have dramatically remodeled various aspects of life sciences,including fundamental research,breeding,and medical therapeutics.So far,four types of endonucleases have been adopted and optimized as gene-editing tools:meganuclease,ZFN,TALEN,and Cas nuclease from the CRISPR-Cas system.Each tool comes with its own advantages and limitations.Over the last ten years,RNA-guided Cas nucleases have been extensively investigated and successfully implemented in almost all mammalian cells due to their remarkable editing efficacy,high specificity,and flexibility in targeting the specific locus.Diverse Cas nuclease,together with meganuclease,ZFN,and TALEN,represent the key strategies for nuclease-based gene editing.However,systematic introductions and comparisons among four types of nucleases are not yet available.Here,we overview the capabilities of four types of nucleases along the development history of gene editing and describe the molecular mechanisms of substrate recognition and cleavage.Particularly,we summarize the promising CRISPR-Cas systems as well as modified tools applied for gene editing in the eukaryotic genome.Moreover,how the re-modulated nucleases and other nucleases,either naturally occurring or AI-designed,might manipulate DNA sequences is discussed and proposed.展开更多
基金supported by a Collaborative Funding Grant from North Carolina Biotechnology Center and Syngenta Biotechnology (2016-CFG-8003)startup funds provided by East Carolina University and University of Maryland to Y.Q.a grant from the National Science Foundation (IOS-1339209)
文摘Breakthroughs in the generation of programmable sequence-specific nucleases (SSNs), such as zinc finger nucleases (ZFNs),TAL effector nucleases (TALENs) and the RNA-directed nuclease CRISPR-associated protein 9 (Cas9), have greatly increased the ease of plant genome engineering (Voytas, 2013; Malzahn et al.,2017). Programmable SSNs introduce a DNA double-strand break
基金the National Institutes of Health R21OD019934(KL)and U42OD011140(RSP)
文摘Pigs are an important resource in agriculture and serve as a model for human diseases. Due to their physiological and anatomical similarities with humans, pigs can recapitulate symptoms of human diseases, making them a useful model in biomedicine. However, in the past pig models have not been widely used partially because of the difficulty in genetic modification. The lack of true embryonic stem cells in pigs forced researchers to utilize genetic modification in somatic cells and somatic cell nuclear transfer(SCNT) to generate genetically engineered(GE) pigs carrying site-specific modifications. Although possible, this approach is extremely inefficient and GE pigs born through this method often presented developmental defects associated with the cloning process. Advancement in the gene-editing systems such as Zinc-Finger Nucleases(ZFNs), Transcription activator-like effector nucleases(TALENs), and the Clustered regularly interspaced short palindromic repeat(CRISPR)/CRISPR-associated 9(Cas9) system have dramatically increased the efficiency of producing GE pigs. These gene-editing systems, specifically engineered endonucleases, are based on inducing double-stranded breaks(DSBs) at a specific location, and then site-specific modifications can be introduced through one of the two DNA repair pathways: non-homologous end joining(NHEJ) or homology direct repair(HDR).Random insertions or deletions(indels) can be introduced through NHEJ and specific nucleotide sequences can be introduced through HDR, if donor DNA is provided. Use of these engineered endonucleases provides a higher success in genetic modifications, multiallelic modification of the genome, and an opportunity to introduce site-specific modifications during embryogenesis, thus bypassing the need of SCNT in GE pig production. This review will provide a historical prospective of GE pig production and examples of how the gene-editing system, led by engineered endonucleases, have improved GE pig production. We wil also present some of our current progress relate
基金partially supported by the grants from National Program on Key Basic Research Project(973 program)(Nos.2012CB945101 and 201 ICBAO 1000)National Natural Science Foundation of China(NSFC)(Nos. 31110103904 and 30730056)
文摘Zebrafish（Danio rerio） is a well-established vertebrate animal model.A comprehensive collection of reverse genetics tools has been developed for studying gene function in this useful organism.Morpholino is the most widely used reagent to knock down target gene expression post-transcriptionally.For a long time,targeted genome modification has been heavily relied on large-scale traditional forward genetic screens,such as ENU（N-ethyl-N-nitrosourea） mutagenesis derived TILLING（Targeting Induced Local Lesions IN Genomes） strategy and pseudo-typed retrovirus mediated insertional mutagenesis.Recently,engineered endonucleases,including ZFNs（zinc finger nucleases） and TALENs（transcription activator-like effector nucleases）,provide new and efficient strategies to directly generate site-specific indel mutations by inducing double strand breaks in target genes.Here we summarize the major reverse genetic approaches for loss-of-function studies used and emerging in zebrafish,including strategies based on genome-wide mutagenesis and methods for site-specific gene targeting.Future directions and expectations will also be discussed.
基金supported by the Ministry of Agriculture and Rural Affairs of Chinathe National Natural Science Foundation of China(32150018)start-up funds from Tsinghua University,Beijing(J.J.G.L.)
文摘In recent decades,gene-editing technologies,typically based on deoxyribonucleases to specifically modify genomic sequences,have dramatically remodeled various aspects of life sciences,including fundamental research,breeding,and medical therapeutics.So far,four types of endonucleases have been adopted and optimized as gene-editing tools:meganuclease,ZFN,TALEN,and Cas nuclease from the CRISPR-Cas system.Each tool comes with its own advantages and limitations.Over the last ten years,RNA-guided Cas nucleases have been extensively investigated and successfully implemented in almost all mammalian cells due to their remarkable editing efficacy,high specificity,and flexibility in targeting the specific locus.Diverse Cas nuclease,together with meganuclease,ZFN,and TALEN,represent the key strategies for nuclease-based gene editing.However,systematic introductions and comparisons among four types of nucleases are not yet available.Here,we overview the capabilities of four types of nucleases along the development history of gene editing and describe the molecular mechanisms of substrate recognition and cleavage.Particularly,we summarize the promising CRISPR-Cas systems as well as modified tools applied for gene editing in the eukaryotic genome.Moreover,how the re-modulated nucleases and other nucleases,either naturally occurring or AI-designed,might manipulate DNA sequences is discussed and proposed.
