Ontology highlight
ABSTRACT:
PROVIDER: PRJNA803880 | ENA |
REPOSITORIES: ENA
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Project description:The RNA-guided DNA endonuclease Cas9 has emerged as a powerful new tool for genome engineering. Cas9 creates targeted double-strand breaks (DSBs) in the genome. Knock-in of specific mutations (precision genome editing) requires homology-directed repair (HDR) of the DSB by synthetic donor DNAs containing the desired edits, but HDR has been reported to be variably efficient. Here, we report that linear DNAs (single and double-stranded) engage in a high-efficiency HDR mechanism that requires only ~35 nucleotides of homology with the targeted locus to introduce edits ranging from 1 to 1000 nucleotides. We demonstrate the utility of linear donors by introducing fluorescent protein tags in human cells and mouse embryos using PCR fragments. We find that repair is local, polarity-sensitive, and prone to template switching, characteristics that are consistent with gene conversion by synthesis-dependent strand-annealing (SDSA). Our findings enable rational design of synthetic donor DNAs for efficient genome editing.
2017-12-01 | GSE107546 | GEO
Project description:The moss Physcomitrella patens is remarkable for the ease with which mutant alleles of any gene can be generated by highly efficient homologous recombination-mediated gene targeting. Targeted transgene integration is believed to be mediated through the capture of transforming DNA by the homologous recombination DNA repair pathway. To identify components of this pathway in P. patens we have undertaken a transcriptomic analysis of the response to the sublethal induction of bleomycin-induced DNA double-strand breaks using massively parallel (Illumina) cDNA sequencing. Transcripts significantly increased in bleomycin-treated tissue include a number encoding conserved DNA-DSB components in both the homology-dependent pathway (including Rad51, CTiP, DNA ligase 1, Replication protein A, ATR) and the non-homologous end-joining pathway (including Xrcc4, DNA ligase 4, Ku70, Ku80, PARP). Differentially regulated cell-cycle components include up-regulated Rad9 and Hus1 DNA-damage-related checkpoint proteins and down-regulated D-type cyclins and B-type CDKs, commensurate with the imposition of a checkpoint in the G2 stage of the cell cycle characteristic of homology-dependent DNA-DSB repair. Comparison of the DNA damage transcriptome of P. patens with that of A. thaliana reveals significant up-regulation of a number of P. patens genes encoding ATP-dependent chromatin remodelling helicases of the SNF-2 class. These represent candidates for investigation of their role in mediating efficient gene targeting in P. patens. Gene expression profiling monitored by transcript abundance in control tissue and tissue treated with the DNA-DSB inducing agent, bleomycin
2010-11-10 | E-GEOD-25237 | biostudies-arrayexpress
Project description:Prime editing is a versatile genome-editing technique that shows great promise for the generation and repair of patient mutations. However, some genomic sites are difficult to edit and optimal design of prime-editing tools remains elusive. Here we present a fluorescent prime editing and enrichment reporter (fluoPEER), which can be tailored to any genomic target site. This system rapidly and faithfully ranks the efficiency of prime edit guide RNAs (pegRNAs) combined with any prime editor variant. We apply fluoPEER to instruct correction of pathogenic variants in patient cells and find that plasmid-editing enriches for genomic editing up to 3-fold compared to conventional enrichment strategies. DNA repair and cell cycle-related genes are enriched in the transcriptome of edited cells. Stalling cells in the G1/S boundary increases prime editing efficiency up to 30%. Together, our results show that fluoPEER can be employed for rapid and efficient correction of patient cells, selection of gene-edited cells, and elucidation of cellular mechanisms needed for successful prime editing.
2022-02-03 | GSE195977 | GEO
Project description:Gene disruption by CRISPR/Cas9 is highly efficient and relies on the error-prone non-homologous end-joining (NHEJ) pathway. Conversely, precise gene editing requires homology-directed repair (HDR), which occurs at a lower frequency than NHEJ in mammalian cells. Here, by testing whether manipulation of DNA repair factors would improve HDR efficacy, we show that transient ectopic co-expression of RAD52 and a dominant-negative 53BP1 (dn53BP1) synergize to enable efficient HDR using a single-stranded oligonucleotide DNA donor template at multiple loci in human cells, including patient-derived induced pluripotent stem (iPS) cells. Co-expression of RAD52 and dn53BP1 improves multiplexed HDR-mediated editing, whereas expression of RAD52 alone enhances HDR with Cas9 nickase. Our data show that the frequency of NHEJ-mediated DSB repair in the presence of these two factors is not suppressed, and suggest that dn53BP1 competitively antagonizes 53BP1 to augment HDR in combination with RAD52. Importantly, co-expression of RAD52 and dn53BP1 does not alter Cas9 off-target activity. These findings support the use of RAD52 and dn53BP1 co-expression to overcome bottlenecks that limit HDR in precision genome editing.
2017-11-23 | GSE103241 | GEO
Project description:Homologous recombination (HR) is an ubiquitous DNA double-strand break (DSB) repair mechanism. It entails a homology search step, carried out along a conserved RecA/Rad51-ssDNA nucleoprotein filament (NPF) assembled on each DSB ends. In contrast to the extensive knowledge of DNA damage checkpoint (DDC)-induced changes in chromatin composition and mobility, the questions of if, how, and to what extent a DSB impacts the spatial organization of chromatin, and whether this organization in turn influences the homology search process, remain ill-defined. Here we characterize two layers of spatial chromatin reorganization following DSB formation in S. cerevisiae. While cohesin folds chromosomes into cohesive arrays of ~20 kb-long chromatin loops as cells arrest in G2/M, the DSB-flanking regions interact locally in a resection- and 9-1-1 clamp-dependent manner, independently of cohesin, Mec1ATR, Rad52 and Rad51. This local structure blocks cohesin progression, constraining the DSB region at the base of a loop. Functionally, cohesin promotes DSB-dsDNA interactions and donor identification in cis, while inhibiting them in trans. This study identifies multiple direct and indirect ways by which cohesin regulates homology search during HR repair.
2021-07-21 | GSE179641 | GEO
Project description:Homologous recombination (HR) is an ubiquitous DNA double-strand break (DSB) repair mechanism. It entails a homology search step, carried out along a conserved RecA/Rad51-ssDNA nucleoprotein filament (NPF) assembled on each DSB ends. In contrast to the extensive knowledge of DNA damage checkpoint (DDC)-induced changes in chromatin composition and mobility, the questions of if, how, and to what extent a DSB impacts the spatial organization of chromatin, and whether this organization in turn influences the homology search process, remain ill-defined. Here we characterize two layers of spatial chromatin reorganization following DSB formation in S. cerevisiae. While cohesin folds chromosomes into cohesive arrays of ~20 kb-long chromatin loops as cells arrest in G2/M, the DSB-flanking regions interact locally in a resection- and 9-1-1 clamp-dependent manner, independently of cohesin, Mec1ATR, Rad52 and Rad51. This local structure blocks cohesin progression, constraining the DSB region at the base of a loop. Functionally, cohesin promotes DSB-dsDNA interactions and donor identification in cis, while inhibiting them in trans. This study identifies multiple direct and indirect ways by which cohesin regulates homology search during HR repair.
2021-07-21 | GSE179638 | GEO
Project description:The moss Physcomitrella patens is remarkable for the ease with which mutant alleles of any gene can be generated by highly efficient homologous recombination-mediated gene targeting. Targeted transgene integration is believed to be mediated through the capture of transforming DNA by the homologous recombination DNA repair pathway. To identify components of this pathway in P. patens we have undertaken a transcriptomic analysis of the response to the sublethal induction of bleomycin-induced DNA double-strand breaks using massively parallel (Illumina) cDNA sequencing. Transcripts significantly increased in bleomycin-treated tissue include a number encoding conserved DNA-DSB components in both the homology-dependent pathway (including Rad51, CTiP, DNA ligase 1, Replication protein A, ATR) and the non-homologous end-joining pathway (including Xrcc4, DNA ligase 4, Ku70, Ku80, PARP). Differentially regulated cell-cycle components include up-regulated Rad9 and Hus1 DNA-damage-related checkpoint proteins and down-regulated D-type cyclins and B-type CDKs, commensurate with the imposition of a checkpoint in the G2 stage of the cell cycle characteristic of homology-dependent DNA-DSB repair. Comparison of the DNA damage transcriptome of P. patens with that of A. thaliana reveals significant up-regulation of a number of P. patens genes encoding ATP-dependent chromatin remodelling helicases of the SNF-2 class. These represent candidates for investigation of their role in mediating efficient gene targeting in P. patens.
2010-11-10 | GSE25237 | GEO
Project description:Prime editing is a novel genome editing technology using fusion proteins of Cas9-nickase and reverse transcriptase, that holds promise to correct a wide variety of genetic defects.
We succeeded in efficient prime editing and functional recovery of disease-causing mutations in patient-derived liver and intestinal stem cell organoids. Whole genome sequencing of did not detect off-target mutations or a mutational signature induced by prime editing.
| EGAS00001004611 | EGA