Project description:Programmable nucleases and designer-recombinases are prominent genome editing tools that hold great potential for the treatment of human genetic disorders. However, both of these tools alone are not optimal for clinical applications. We present an approach that combines the ease of targeting of programmable nucleases with editing safety and accuracy of site-specific recombinases. We find that insertional fusions of zinc-finger DNA-binding domains (ZFDs) into the coding sequence of designer-recombinases generate conditional enzymes that are inactive, unless the ZFD binds its target site placed in the vicinity of the recombinase binding site. This induced-fit activity is transferable to a recombinase with relaxed specificity, representing the prototype of a new class of genome editing enzymes that opens exciting perspectives for flexible, seamless, and precise genome surgery.
Project description:Half of all human transcription factors use C2H2 zinc finger domains to specify site-specific DNA binding and yet very little is known about their role in gene regulation. Based on in vitro studies, a zinc finger code has been developed that predicts a binding motif for a particular zinc finger factor (ZNF). However, very few studies have performed genome-wide analyses of ZNF binding patterns and thus it is not clear if the binding code developed in vitro will be useful for identifying target genes of a particular ZNF. We performed genome-wide ChIP-seq for ZNF263, a C2H2 ZNF that contains 9 finger domains, a KRAB repression domain, and a SCAN domain and identified more than 5000 binding sites in K562 cells. Our results suggest that ZNF263 binds to a 24 nt site which differs from the motif predicted by the zinc finger code in several positions. Interestingly, many of the ZNF263 binding sites are located within the transcribed region of the target gene. Although ZNFs containing a KRAB domain are thought to function mainly as transcriptional repressors, many of the ZNF263 target genes are expressed at high levels. To address the biological role of ZNF263, we identified genes whose expression was altered by treatment of cells with ZNF263-specific siRNAs. Our results suggest that ZNF263 can have both positive and negative effects on transcriptional regulation of its target genes. For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODEDataReleasePolicyFinal2008.pdf Examination of ZNF263 ChIP-seq in K562 cells.
Project description:The largest and most diverse class of eukaryotic transcription factors contain Cys2-His2 zinc fingers (C2H2-ZFs), each of which typically binds a DNA nucleotide triplet within a larger binding site. Frequent recombination and diversification of their DNA-contacting residues suggests that these zinc fingers play a prevalent role in adaptive evolution. Very little is known about the function and evolution of the vast majority of C2H2-ZFs, including whether they even bind DNA. Using the bacterial 1-hybrid (B1H) system, we determined DNA-binding motifs for thousands of individual natural C2H2-ZFs, and correlated them with C2H2-ZF specificity residues. The data reported here includes results of protein-binding microarray (PBM) assays for 146 of these natural C2H2-ZFs, performed in order to validate B1H assays and to explore the DNA-binding specificity of C2H2-ZFs. Protein binding microarray (PBM) experiments were performed for a set of 185 variants of mouse Egr1 in which the third zinc finger was replaced by different C2H2-ZFs from different organisms. Briefly, the PBMs involved binding GST-tagged DNA-binding proteins to two double-stranded 44K Agilent microarrays, each containing a different DeBruijn sequence design, in order to determine their sequence preferences. Details of the PBM protocol are described in Berger et al., Nature Biotechnology 2006. Among the 185 variants examined, 146 variants yielded motifs in PBMs, which are included here.
Project description:C2H2 zinc finger proteins represent the largest and most enigmatic class of human transcription factors. Their C2H2 arrays are highly variable, indicating that most will have unique DNA binding motifs. However, most of the binding motifs have not been directly determined. We have determined the binding sites and motifs of 119 C2H2 zinc finger proteins and the expression pattern of 80 cell lines overexpressing C2H2 zinc finger proteins in order to study the role of C2H2 zinc finger proteins in gene regulation. We expressed GFP-tagged C2H2-ZF proteins in stable transgenic HEK293 cells. Total RNA was isolated using Trizol and sequencing libraries were constructed using TruSeq Stranded Total RNA Library Prep Kit with Ribo-Zero Gold or TruSeq RNA Library Preparation Kit v2.
Project description:C2H2 zinc finger proteins represent the largest and most enigmatic class of human transcription factors. Their C2H2 arrays are highly variable, indicating that most will have unique DNA binding motifs. However, most of the binding motifs have not been directly determined. We have determined the binding sites and motifs of 119 C2H2 zinc finger proteins and the expression pattern of 80 cell lines overexpressing C2H2 zinc finger proteins in order to study the role of C2H2 zinc finger proteins in gene regulation.
Project description:Half of all human transcription factors use C2H2 zinc finger domains to specify site-specific DNA binding and yet very little is known about their role in gene regulation. Based on in vitro studies, a zinc finger code has been developed that predicts a binding motif for a particular zinc finger factor (ZNF). However, very few studies have performed genome-wide analyses of ZNF binding patterns and thus it is not clear if the binding code developed in vitro will be useful for identifying target genes of a particular ZNF. We performed genome-wide ChIP-seq for ZNF263, a C2H2 ZNF that contains 9 finger domains, a KRAB repression domain, and a SCAN domain and identified more than 5000 binding sites in K562 cells. Our results suggest that ZNF263 binds to a 24 nt site which differs from the motif predicted by the zinc finger code in several positions. Interestingly, many of the ZNF263 binding sites are located within the transcribed region of the target gene. Although ZNFs containing a KRAB domain are thought to function mainly as transcriptional repressors, many of the ZNF263 target genes are expressed at high levels. To address the biological role of ZNF263, we identified genes whose expression was altered by treatment of cells with ZNF263-specific siRNAs. Our results suggest that ZNF263 can have both positive and negative effects on transcriptional regulation of its target genes.
Project description:Half of all human transcription factors use C2H2 zinc finger domains to specify site-specific DNA binding and yet very little is known about their role in gene regulation. Based on in vitro studies, a zinc finger code has been developed that predicts a binding motif for a particular zinc finger factor (ZNF). However, very few studies have performed genome-wide analyses of ZNF binding patterns and thus it is not clear if the binding code developed in vitro will be useful for identifying target genes of a particular ZNF. We performed genome-wide ChIP-seq for ZNF263, a C2H2 ZNF that contains 9 finger domains, a KRAB repression domain, and a SCAN domain and identified more than 5000 binding sites in K562 cells. Our results suggest that ZNF263 binds to a 24 nt site which differs from the motif predicted by the zinc finger code in several positions. Interestingly, many of the ZNF263 binding sites are located within the transcribed region of the target gene. Although ZNFs containing a KRAB domain are thought to function mainly as transcriptional repressors, many of the ZNF263 target genes are expressed at high levels. To address the biological role of ZNF263, we identified genes whose expression was altered by treatment of cells with ZNF263-specific siRNAs. Our results suggest that ZNF263 can have both positive and negative effects on transcriptional regulation of its target genes. For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODEDataReleasePolicyFinal2008.pdf
Project description:We have identified protein protein interactions of 118 C2H2 zinc finger proteins by AP-MS using GFP-tagged constructs in order to understand their role in transcription regulation.
Project description:Zinc Finger Nucleases (ZFNs) facilitate precise editing of DNA enabling targeted genomic modifications in vivo. ZFNs have been employed to obtain genetically modified plants and animals, and cell-based therapies utilizing ZFNs are undergoing clinical trials. However, many ZFNs display dose-dependent toxicity presumably due to the generation of undesired double stranded breaks at off-target sites within the genome. To evaluate the parameters influencing the functional specificity of ZFNs, we compared the in vivo activity of ZFN variants targeting the zebrafish kdrl locus, which display both high on-target activity and dose-dependent toxicity. We evaluated their functional specificity by assessing lesion frequency at 141 potential off-target sites within the zebrafish genome using Illumina sequencing. Only a minority of these off-target sites displayed significant lesion frequency with kdrl ZFNs. Furthermore, we find that active off-target sites appear to be defined by the thermodynamics of zinc finger-DNA recognition. Surprisingly, we observed that the zinc finger protein specificity and the choice of the engineered dimerization domain of the FokI nuclease could independently influence the fidelity of these ZFNs. The results of this study have implications for the assessment of likely off-target sites within a genome and point to both ZFP-dependent and –independent mechanisms of potential improvement for engineering ZFNs with higher levels of precision. Examined lesions at 141 off-target sites for various treatments of ZFNs and compare to the untreated sample stage 1: raw read but missing quality values stage 2: fastq files available from SRA