Person: Reyon, Deepak
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Reyon
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Deepak
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Reyon, Deepak
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Publication Targeted Deletion and Inversion of Tandemly Arrayed Genes in Arabidopsis thaliana Using Zinc Finger Nucleases(Genetics Society of America, 2013) Qi, Yiping; Li, Xiaohong; Zhang, Yong; Starker, Colby G.; Baltes, Nicholas J.; Zhang, Feng; Sander, Jeffry D.; Reyon, Deepak; Joung, J. Keith; Voytas, Daniel F.Tandemly arrayed genes (TAGs) or gene clusters are prevalent in higher eukaryotic genomes. For example, approximately 17% of genes are organized in tandem in the model plant Arabidopsis thaliana. The genetic redundancy created by TAGs presents a challenge for reverse genetics. As molecular scissors, engineered zinc finger nucleases (ZFNs) make DNA double-strand breaks in a sequence-specific manner. ZFNs thus provide a means to delete TAGs by creating two double-strand breaks in the gene cluster. Using engineered ZFNs, we successfully targeted seven genes from three TAGs on two Arabidopsis chromosomes, including the well-known RPP4 gene cluster, which contains eight resistance (R) genes. The resulting gene cluster deletions ranged from a few kb to 55 kb with frequencies approximating 1% in somatic cells. We also obtained large chromosomal deletions of ~9 Mb at approximately one tenth the frequency, and gene cluster inversions and duplications also were achieved. This study demonstrates the ability to use sequence-specific nucleases in plants to make targeted chromosome rearrangements and create novel chimeric genes for reverse genetics and biotechnology.Publication In silico abstraction of zinc finger nuclease cleavage profiles reveals an expanded landscape of off-target sites(Oxford University Press, 2013) Sander, Jeffry D.; Ramirez, Cherie Lynn; Linder, Sam; Pattanayak, Vikram; Shoresh, Noam; Ku, Manching; Foden, Jennifer A.; Reyon, Deepak; Bernstein, Bradley; Liu, David; Joung, J. KeithGene-editing nucleases enable targeted modification of DNA sequences in living cells, thereby facilitating efficient knockout and precise editing of endogenous loci. Engineered nucleases also have the potential to introduce mutations at off-target sites of action. Such unintended alterations can confound interpretation of experiments and can have implications for development of therapeutic applications. Recently, two improved methods for identifying the off-target effects of zinc finger nucleases (ZFNs) were described–one using an in vitro cleavage site selection method and the other exploiting the insertion of integration-defective lentiviruses into nuclease-induced double-stranded DNA breaks. However, application of these two methods to a ZFN pair targeted to the human CCR5 gene led to identification of largely non-overlapping off-target sites, raising the possibility that additional off-target sites might exist. Here, we show that in silico abstraction of ZFN cleavage profiles obtained from in vitro cleavage site selections can greatly enhance the ability to identify potential off-target sites in human cells. Our improved method should enable more comprehensive profiling of ZFN specificities.Publication Heritable and Precise Zebrafish Genome Editing Using a CRISPR-Cas System(Public Library of Science, 2013) Hwang, Woong Y.; Fu, Yanfang; Reyon, Deepak; Maeder, Morgan L.; Kaini, Prakriti; Sander, Jeffry D.; Joung, J. Keith; Peterson, Randall; Yeh, Jing-RueyWe have previously reported a simple and customizable CRISPR (clustered regularly interspaced short palindromic repeats) RNA-guided Cas9 nuclease (RGN) system that can be used to efficiently and robustly introduce somatic indel mutations in endogenous zebrafish genes. Here we demonstrate that RGN-induced mutations are heritable, with efficiencies of germline transmission reaching as high as 100%. In addition, we extend the power of the RGN system by showing that these nucleases can be used with single-stranded oligodeoxynucleotides (ssODNs) to create precise intended sequence modifications, including single nucleotide substitutions. Finally, we describe and validate simple strategies that improve the targeting range of RGNs from 1 in every 128 basepairs (bps) of random DNA sequence to 1 in every 8 bps. Together, these advances expand the utility of the CRISPR-Cas system in the zebrafish beyond somatic indel formation to heritable and precise genome modifications.Publication Robust, synergistic regulation of human gene expression using TALE activators(2013) Maeder, Morgan L.; Linder, Sam; Reyon, Deepak; Angstman, James; Fu, Yanfang; Sander, Jeffry D.; Joung, J. KeithArtificial transcription activator-like (TAL) effector-based activators (TALE activators) have broad utility but previous studies suggest that these monomeric proteins often possess low activities. Here we demonstrate that TALE activators can robustly function individually or in synergistic combinations to increase expression of endogenous human genes over wide dynamic ranges. These findings will encourage applications of TALE activators for research and therapy and guide design of novel monomeric TAL effector-based fusion proteins.Publication Efficient In Vivo Genome Editing Using RNA-Guided Nucleases(2013) Hwang, Woong Y.; Fu, Yanfang; Reyon, Deepak; Maeder, Morgan L.; Tsai, Shengdar Q.; Sander, Jeffry D.; Peterson, Randall; Yeh, J.-R. Joanna; Joung, J. KeithClustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) systems have evolved in bacteria and archaea as a defense mechanism to silence foreign nucleic acids of viruses and plasmids. Recent work has shown that bacterial type II CRISPR systems can be adapted to create guide RNAs (gRNAs) capable of directing site-specific DNA cleavage by the Cas9 nuclease in vitro. Here we show that this system can function in vivo to induce targeted genetic modifications in zebrafish embryos with efficiencies comparable to those obtained using ZFNs and TALENs for the same genes. RNA-guided nucleases robustly enabled genome editing at 9 of 11 different sites tested, including two for which TALENs previously failed to induce alterations. These results demonstrate that programmable CRISPR/Cas systems provide a simple, rapid, and highly scalable method for altering genes in vivo, opening the door to using RNA-guided nucleases for genome editing in a wide range of organisms.Publication High frequency off-target mutagenesis induced by CRISPR-Cas nucleases in human cells(2013) Fu, Yanfang; Foden, Jennifer A.; Khayter, Cyd; Maeder, Morgan L.; Reyon, Deepak; Joung, J. Keith; Sander, Jeffry D.CRISPR RNA-guided endonucleases (RGENs) have rapidly emerged as a facile and efficient platform for genome editing. Here, we use a human cell-based reporter assay to characterize off-target cleavage of Cas9-based RGENs. We find that single and double mismatches are tolerated to varying degrees depending on their position along the guide RNA (gRNA)-DNA interface. We readily detected off-target alterations induced by four out of six RGENs targeted to endogenous loci in human cells by examination of partially mismatched sites. The off-target sites we identified harbor up to five mismatches and many are mutagenized with frequencies comparable to (or higher than) those observed at the intended on-target site. Our work demonstrates that RGENs are highly active even with imperfectly matched RNA-DNA interfaces in human cells, a finding that might confound their use in research and therapeutic applications.Publication Improved Somatic Mutagenesis in Zebrafish Using Transcription Activator-Like Effector Nucleases (TALENs)(Public Library of Science, 2012) Moore, Finola E.; Reyon, Deepak; Sander, Jeffry D.; Martinez, Sarah A.; Blackburn, Jessica S.; Khayter, Cyd; Ramirez, Cherie Lynn; Joung, Keith; Langenau, DavidZinc Finger Nucleases (ZFNs) made by Context-Dependent Assembly (CoDA) and Transcription Activator-Like Effector Nucleases (TALENs) provide robust and user-friendly technologies for efficiently inactivating genes in zebrafish. These designer nucleases bind to and cleave DNA at particular target sites, inducing error-prone repair that can result in insertion or deletion mutations. Here, we assess the relative efficiencies of these technologies for inducing somatic DNA mutations in mosaic zebrafish. We find that TALENs exhibited a higher success rate for obtaining active nucleases capable of inducing mutations than compared with CoDA ZFNs. For example, all six TALENs tested induced DNA mutations at genomic target sites while only a subset of CoDA ZFNs exhibited detectable rates of mutagenesis. TALENs also exhibited higher mutation rates than CoDA ZFNs that had not been pre-screened using a bacterial two-hybrid assay, with DNA mutation rates ranging from 20%–76.8% compared to 1.1%–3.3%. Furthermore, the broader targeting range of TALENs enabled us to induce mutations at the methionine translation start site, sequences that were not targetable using the CoDA ZFN platform. TALENs exhibited similar toxicity to CoDA ZFNs, with >50% of injected animals surviving to 3 days of life. Taken together, our results suggest that TALEN technology provides a robust alternative to CoDA ZFNs for inducing targeted gene-inactivation in zebrafish, making it a preferred technology for creating targeted knockout mutants in zebrafish.Publication Highly Efficient Generation of Heritable Zebrafish Gene Mutations Using Homo- and Heterodimeric TALENs(Oxford University Press, 2012) Cade, Lindsay; Reyon, Deepak; Hwang, Woong Y.; Tsai, Shengdar Q.; Patel, Samir; Khayter, Cyd; Joung, Keith; Sander, Jeffry D.; Peterson, Randall; Yeh, Jing-RueyTranscription activator-like effector nucleases (TALENs) are powerful new research tools that enable targeted gene disruption in a wide variety of model organisms. Recent work has shown that TALENs can induce mutations in endogenous zebrafish genes, but to date only four genes have been altered, and larger-scale tests of the success rate, mutation efficiencies and germline transmission rates have not been described. Here, we constructed homodimeric TALENs to 10 different targets in various endogenous zebrafish genes and found that 7 nuclease pairs induced targeted indel mutations with high efficiencies ranging from 2 to 76%. We also tested obligate heterodimeric TALENs and found that these nucleases induce mutations with comparable or higher frequencies and have better toxicity profiles than their homodimeric counterparts. Importantly, mutations induced by both homodimeric and heterodimeric TALENs are passed efficiently through the germline, in some cases reaching 100% transmission. For one target gene sequence, we observed substantially reduced mutagenesis efficiency for a variant site bearing two mismatched nucleotides, raising the possibility that TALENs might be used to perform allele-specific gene disruption. Our results suggest that construction of one to two heterodimeric TALEN pairs for any given gene will, in most cases, enable researchers to rapidly generate knockout zebrafish.Publication Identification of promoter targets of enhancers by epigenetic knockdown using TAL DNA binding proteins(BioMed Central, 2013) Mendenhall, Eric M; Williamson, Kaylyn; Reyon, Deepak; Joung, Keith; Bernstein, Bradley