Project description:Genome editing typically involves recombination between donor nucleic acids and genomic sequences subjected to double-stranded DNA breaks (DSBs) made by programmable nucleases (e.g. CRISPR-Cas9). Yet, amongst other deleterious by-products, DSBs yield translocations, off-target mutations and, most pervasively, unpredictable on-target allelic disruptions. Remarkably, hitherto, the untoward phenotypic consequences of on-target disruptions at allelic and non-allelic (e.g. pseudogene) sequences have received scant scrutiny and, crucially, remain to be addressed. Here, we demonstrate that gene-edited cells can lose fitness due to on-target DSBs and report that simultaneous single-stranded DNA break formation at donor and target DNA by CRISPR-Cas9 “nickases” overcomes, to a great extent, such genotype-phenotype disrupting events. Moreover, in trans paired nicking gene editing can efficiently and precisely add large DNA segments (i.e. live-cell reporter tags) into essential and multiple-copy genomic sequences while circumventing most of the allelic and non-allelic collateral mutations and chromosomal rearrangements characteristic of nuclease-dependent gene editing procedures.
Project description:MLL3 inactivation mutations occurs frequently in human breast cancer. To understand the function of MLL3 inactivation, we compared the gene expression profiles of the vector control (WT) and Mll3-knockout MCF7 cells generated by CRISPR-CAS9. Affymetrix human Gene 2.0ST arrays were used for microarray.
Project description:Heterozygous and homozygous mutations were introduced to the human embryonic stem cell line H9 by using the CRISPR/Cas9-system. Since off-target effects can occur and high numbers of SNVs can be acquired during clonal selection, the generated cell lines and the parental cell line were analyzed by whole-genome sequencing.
Project description:The role of ARID4B in breast cancer development has not been completely elucidated. The aim of this study was to investigate the effect of loss of function mutations generated using the CRISPR/Cas9 system in human breast cancer cells. For this, we characterized the proliferation, viability, and migration rates of different clones with insertions and deletions compared to wild-type cells. We report the transcriptomic profile of mutated MCF-7 clones and negative control.
Project description:In order to investigate the roles of retinoblastoma family genes during early human development, mutant H9 human embryonic stem cells were generated. Frameshift mutations were introduced in RBL1 and RBL2 genes using the CRISPR/Cas9 technology, and then the shRNA-expression cassette to knockdown RB upon tetracycline treatment was integrated. These cells were cultured in definitive endoderm differentiation conditions for 3 or 6 days with/without tetracycline.
Project description:We generated a SNORD71 KO chondrocyte cell pool using CRISPR/Cas9 gene editing. A CRISPR control cell line was generated and used as a control. Levels of 2’-O-methylation of human rRNAs in SNORD71 KO cell pool and CRISPR control cells were evaluated by RiboMethSeq.
Project description:Most loci contributing to breast cancer susceptibility identified by the recent genome-wide association studies (GWAS) are predicted to have a regulatory function. Additionally, the early phases of the GWAS studies have generated long lists of possible candidates that need to be prioritised for follow-up studies. Integration of allelic expression mapping and disease association data should enable the identification of those GWAS hits with higher cis-regulatory potential. Our aims are (1) to assess how well functional data and disease risk are correlated and (2) to help prioritise and select the strongest candidates from the GWAS scan for further follow-up and functional analysis. We are performing genome-wide differential allelic expression (DAE) analysis to identify loci with cis-regulatory potential in sixty-four normal breast tissue samples. Using the Illumina Exon510S-Duo BeadChips, we have identified 34K informative SNPs of which approximately 8K (23.5%) displayed DAE. Two SNPs showed monoallelic expression suggesting possible new imprinted loci. We are mapping the cis-regulatory loci by fitting a linear regression model with permutations to DAE ratios vs genotype at SNPs within ±250kb of the RefSeq gene corresponding to the DAE SNP. We will combine our data with the UK GWAS1 and GWAS2 studies for breast cancer susceptibility, to generate a list of genes that show regulatory variation for further evaluation as candidates. This is the first genome-wide differential allelic expression study in normal breast tissue, and one of the first in a primary tissue. We predict that this will be a powerful approach to validate/identify susceptibility loci and to unravel some of the biology underlying breast cancer susceptibility. Allelic gene expression of normal breast sample from healthy controls.
Project description:Hepatocyte nuclear factor 1B (HNF1B) encodes a transcription factor expressed in developing human kidney epithelia. Heterozygous HNF1B mutations are the commonest monogenic cause of dysplastic kidney malformations (DKMs). To understand their pathobiology, we generated heterozygous HNF1B mutant kidney organoids from CRISPR-Cas9 gene-edited human ESCs and iPSCs reprogrammed from a family with HNF1B-asscociated DKMs. Mutant organoids contained enlarged malformed tubules and displayed deregulated cell turnover. This submission contains kidney tissue samples.
Project description:APOBEC-AID family of cytidine deaminase prefers single-stranded nucleic acids for cytidine to uracil deamination. Single-stranded nucleic acids are commonly involved in the DNA repair system for breaks generated by CRISPR-Cas9. Here, we show in human cells that APOBEC3s can trigger the cytidine deamination of single-stranded oligodeoxynucleotides, which ultimately results in base substitution mutations in genomic DNA through the homology-directed repair (HDR) of Cas9-generated double-strand breaks . In addition, the APOBEC3-catalyzed deamination in genomic single-stranded DNA formed during the repair of Cas9 nickase-generated single-strand breaks can be further processed to yield mutations mainly involving insertions or deletions (indels). Mechanistically, both APOBEC3-mediated deamination and DNA repair proteins play important roles in the generation of these indels. Correspondingly, optimizing conditions for the repair of CRISPR-Cas9-generated DNA breaks, such as using double-stranded donors in HDR or temporarily suppressing endogenous APOBEC3s, can substantially repress these unwanted mutations in genomic DNA.
