Selection-free zinc-finger-nuclease engineering by context-dependent assembly (CoDA).
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ABSTRACT:
SUBMITTER: Sander JD
PROVIDER: S-EPMC3018472 | biostudies-literature | 2011 Jan
REPOSITORIES: biostudies-literature
Publications
Selection-free zinc-finger-nuclease engineering by context-dependent assembly (CoDA).
Sander Jeffry D JD Dahlborg Elizabeth J EJ Goodwin Mathew J MJ Cade Lindsay L Zhang Feng F Cifuentes Daniel D Curtin Shaun J SJ Blackburn Jessica S JS Thibodeau-Beganny Stacey S Qi Yiping Y Pierick Christopher J CJ Hoffman Ellen E Maeder Morgan L ML Khayter Cyd C Reyon Deepak D Dobbs Drena D Langenau David M DM Stupar Robert M RM Giraldez Antonio J AJ Voytas Daniel F DF Peterson Randall T RT Yeh Jing-Ruey J JR Joung J Keith JK
Nature methods 20101212 1
Engineered zinc-finger nucleases (ZFNs) enable targeted genome modification. Here we describe context-dependent assembly (CoDA), a platform for engineering ZFNs using only standard cloning techniques or custom DNA synthesis. Using CoDA-generated ZFNs, we rapidly altered 20 genes in Danio rerio, Arabidopsis thaliana and Glycine max. The simplicity and efficacy of CoDA will enable broad adoption of ZFN technology and make possible large-scale projects focused on multigene pathways or genome-wide a ...[more]
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Project description:Engineered zinc finger nucleases (ZFNs) are a tool for genome manipulation that are of great interest to scientists in many fields. To meet the needs of researchers wishing to employ ZFNs, an inexpensive, rapid assembly procedure would be beneficial to laboratories that do not have access to the proprietary reagents often required for ZFN production. Using freely available sequence data derived from the Zinc Finger Targeter database, we developed a protocol for synthesis and directed insertion of user-defined ZFNs into a versatile plasmid expression system. This oligonucleotide-based isothermal DNA assembly protocol was used to determine whether we could generate functional nucleases capable of endogenous gene editing. We targeted the human α-l-iduronidase (IDUA) gene on chromosome 4, mutations of which result in the severe lysosomal storage disease mucopolysaccharidosis type I. In approximately 1 week we were able to design, assemble, and test six IDUA-specific ZFNs. In a single-stranded annealing assay five of the six candidates we tested performed at a level comparable to or surpassing previously reported ZFNs. One of the five subsequently showed nuclease activity at the endogenous genomic IDUA locus. To our knowledge, this is the first demonstration of in silico-designed, oligonucleotide-assembled, synthetic ZFNs, requiring no specialized templates or reagents that are capable of endogenous human gene target site activity. This method, termed CoDA-syn (context-dependent assembly-synthetic), should facilitate a more widespread use of ZFNs in the research community.
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Project description:Zinc-finger nucleases (ZFNs) have been successfully used for rational genome engineering in a variety of cell types and organisms. ZFNs consist of a non-specific FokI endonuclease domain and a specific zinc-finger DNA-binding domain. Because the catalytic domain must dimerize to become active, two ZFN subunits are typically assembled at the cleavage site. The generation of obligate heterodimeric ZFNs was shown to significantly reduce ZFN-associated cytotoxicity in single-site genome editing strategies. To further expand the application range of ZFNs, we employed a combination of in silico protein modeling, in vitro cleavage assays, and in vivo recombination assays to identify autonomous ZFN pairs that lack cross-reactivity between each other. In the context of ZFNs designed to recognize two adjacent sites in the human HOXB13 locus, we demonstrate that two autonomous ZFN pairs can be directed simultaneously to two different sites to induce a chromosomal deletion in ∼ 10% of alleles. Notably, the autonomous ZFN pair induced a targeted chromosomal deletion with the same efficacy as previously published obligate heterodimeric ZFNs but with significantly less toxicity. These results demonstrate that autonomous ZFNs will prove useful in targeted genome engineering approaches wherever an application requires the expression of two distinct ZFN pairs.
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Project description:Zinc finger nucleases (ZFN) are powerful tools for editing genes in cells. Here we use ZFNs to interrogate the biological function of human ADPGK, which encodes an ADP-dependent glucokinase (ADPGK), in tumour cell lines. The hypothesis tested is that ADPGK utilises ADP to phosphorylate glucose under conditions where ATP becomes limiting, such as hypoxia. We characterised two ZFN knockout clones in each of two tumour cell lines (H460 and HCT116). All four lines had frameshift mutations in all alleles at the target site in exon 1 of ADPGK, and were ADPGK-null by immunoblotting. ADPGK knockout had little or no effect on cell proliferation, but compromised the ability of H460 cells to survive siRNA silencing of hexokinase-2 under oxic conditions, with clonogenic survival falling from 21±3% for the parental line to 6.4±0.8% (p=0.002) and 4.3±0.8% (p=0.001) for the two knockouts. A similar increased sensitivity to clonogenic cell killing was observed under anoxia. No such changes were found when ADPGK was knocked out in HCT116 cells, for which the parental line was less sensitive than H460 to anoxia and to hexokinase-2 silencing. While knockout of ADPGK in HCT116 cells caused few changes in global gene expression, knockout of ADPGK in H460 cells caused notable up-regulation of mRNAs encoding cell adhesion proteins. Surprisingly, we could discern no effect on glycolysis as measured by glucose consumption or lactate formation under oxic or anoxic conditions, or extracellular acidification rate (Seahorse XF analyser) under oxic conditions in a variety of media. However, oxygen consumption rates were generally lower in the ADPGK knockouts, in some cases markedly so. Collectively, the results demonstrate that ADPGK can contribute to tumour cell survival under conditions of high glycolytic dependence, but the phenotype resulting from knockout of ADPGK is cell line dependent and appears to be unrelated to priming of glycolysis.
2012-07-20 | GSE39497 | GEO
Project description:Zinc-finger nucleases (ZFNs) are targetable DNA cleavage reagents that have been adopted as gene-targeting tools. ZFN-induced double-strand breaks are subject to cellular DNA repair processes that lead to both targeted mutagenesis and targeted gene replacement at remarkably high frequencies. This article briefly reviews the history of ZFN development and summarizes applications that have been made to genome editing in many different organisms and situations. Considerable progress has been made in methods for deriving zinc-finger sets for new genomic targets, but approaches to design and selection are still being perfected. An issue that needs more attention is the extent to which available mechanisms of double-strand break repair limit the scope and utility of ZFN-initiated events. The bright prospects for future applications of ZFNs, including human gene therapy, are discussed.
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