Project description:Using CRISPR/Cas9 for allele-specific genome editing we phenocopied AA symptomatic patched hair loss in mice engineered to carry the Cchcr1 risk allele.
Project description:Epidermolysis Bullosa Simplex (EBS) is the most common form of Epidermolysis Bullosa (EB) and it is mainly inherited in an autosomal dominant manner (prevalence 1/30000 – 1/50000). Several clinical variants have been described based on the mutated gene, the site of blister formation and the anatomical distribution, but the vast majority of the patients display dominant mutations in genes encoding keratin 5 (KRT5) and keratin 14 (KRT14). The lack of functional keratin intermediate filaments causes basal keratinocytes to exhibit a dramatic cytoplasmatic softening and rupture, when subjected to minor mechanical traction, leading to the distinctive EBS patients intraepidermal blisters formation. Whilst viral mediated addition of a corrected copy of the altered gene is the ascertained approach to tackle recessively inherited EB (such as Junctional and Dystrophic EB), a potential successful combined cell and gene therapy for EBS dominant forms requires the editing of the mutated gene. In this case study, we outlined an allele specific CRISPR/Cas9 gene editing approach able to specifically detect and disrupt a de novo monoallelic c.475/495del21 mutation within exon 1 of KRT14. Taking advantage of the tailored CRISPR/Cas9 system to induce a NHEJ mediated frameshift mutations introduction, we attained a remarkable mutant allele knock-out efficiency. Following KRT14 mutant allele specific gene editing, patient derived primary keratinocytes (EBS01) restored a normal intermediate filament network and mechanical stress resilience.
Project description:Epidermolysis Bullosa Simplex (EBS) is the most common form of Epidermolysis Bullosa (EB) and it is mainly inherited in an autosomal dominant manner (prevalence 1/30000 – 1/50000). Several clinical variants have been described based on the mutated gene, the site of blister formation and the anatomical distribution, but the vast majority of the patients display dominant mutations in genes encoding keratin 5 (KRT5) and keratin 14 (KRT14). The lack of functional keratin intermediate filaments causes basal keratinocytes to exhibit a dramatic cytoplasmatic softening and rupture, when subjected to minor mechanical traction, leading to the distinctive EBS patients intraepidermal blisters formation. Whilst viral mediated addition of a corrected copy of the altered gene is the ascertained approach to tackle recessively inherited EB (such as Junctional and Dystrophic EB), a potential successful combined cell and gene therapy for EBS dominant forms requires the editing of the mutated gene. In this case study, we outlined an allele specific CRISPR/Cas9 gene editing approach able to specifically detect and disrupt a de novo monoallelic c.475/495del21 mutation within exon 1 of KRT14. Taking advantage of the tailored CRISPR/Cas9 system to induce a NHEJ mediated frameshift mutations introduction, we attained a remarkable mutant allele knock-out efficiency. Following KRT14 mutant allele specific gene editing, patient derived primary keratinocytes (EBS01) restored a normal intermediate filament network and mechanical stress resilience.
Project description:Next-generation sequencing has become an important tool for genome-wide quantification of DNA and RNA. However, a major technical hurdle lies in the need to map short sequence reads back to their correct locations in a reference genome. Here we investigate the impact of SNP variation on the reliability of read-mapping in the context of detecting allele-specific expression (ASE).We generated sixteen million 35 bp reads from mRNA of each of two HapMap Yoruba individuals. When we mapped these reads to the human genome we found that, at heterozygous SNPs, there was a significant bias towards higher mapping rates of the allele in the reference sequence, compared to the alternative allele. Masking known SNP positions in the genome sequence eliminated the reference bias but, surprisingly, did not lead to more reliable results overall. We find that even after masking, $\sim$5-10\% of SNPs still have an inherent bias towards more effective mapping of one allele. Filtering out inherently biased SNPs removes 40\% of the top signals of ASE. The remaining SNPs showing ASE are enriched in genes previously known to harbor cis-regulatory variation or known to show uniparental imprinting. Our results have implications for a variety of applications involving detection of alternate alleles from short-read sequence data. Scripts, written in Perl and R, for simulating short reads, masking SNP variation in a reference genome, and analyzing the simulation output are available upon request from JFD. RNA-Seq on two YRI Hapmap cell lines. Each individual sequenced on two lanes of the Illumina Genome Analyzer
Project description:Next-generation sequencing has become an important tool for genome-wide quantification of DNA and RNA. However, a major technical hurdle lies in the need to map short sequence reads back to their correct locations in a reference genome. Here we investigate the impact of SNP variation on the reliability of read-mapping in the context of detecting allele-specific expression (ASE).We generated sixteen million 35 bp reads from mRNA of each of two HapMap Yoruba individuals. When we mapped these reads to the human genome we found that, at heterozygous SNPs, there was a significant bias towards higher mapping rates of the allele in the reference sequence, compared to the alternative allele. Masking known SNP positions in the genome sequence eliminated the reference bias but, surprisingly, did not lead to more reliable results overall. We find that even after masking, $\sim$5-10\% of SNPs still have an inherent bias towards more effective mapping of one allele. Filtering out inherently biased SNPs removes 40\% of the top signals of ASE. The remaining SNPs showing ASE are enriched in genes previously known to harbor cis-regulatory variation or known to show uniparental imprinting. Our results have implications for a variety of applications involving detection of alternate alleles from short-read sequence data. Scripts, written in Perl and R, for simulating short reads, masking SNP variation in a reference genome, and analyzing the simulation output are available upon request from JFD.
Project description:Purpose: RNA editing by ADAR1 is essential for hematopoietic development. The goals of this study were firstly, to identify ADAR1-specific RNA-editing sites by indentifying A-to-I (G) mismatches in RNA-seq data compared to mm9 reference genome in wild type mice that were not edited or reduced in editing frequency in ADAR1E861A editing deficient mice. Secondly, to determine the transcriptional consequence of an absence of ADAR1-mediated A-to-I editing. Methods: Fetal liver mRNA profiles of embryonic day 12.5 wild-type (WT) and ADAR1 editing-deficient (ADAR1E861A) mice were generated by RNA sequencing, in triplicate (biological replicates), using Illumina HiSeq2000. The sequence reads that passed quality filters were analyzed at the transcript level with TopHat followed by Cufflinks. qRT–PCR validation was performed using SYBR Green assays. A-to-I (G) RNA editing sites were identified as previously described by Ramaswami G. et al., Nature Methods, 2012 using Burrows–Wheeler Aligner (BWA) followed by ANOVA (ANOVA). RNA editing sites were confirmed by Sanger sequencing. Results: Using an optimized data analysis workflow, we mapped about 30 million sequence reads per sample to the mouse genome (build mm9) and identified 14,484 transcripts in the fetal livers of WT and ADAR1E861A mice with BWA. RNA-seq data had a goodness of fit (R2) of >0.94 between biological triplicates per genotype. Approximately 4.4% of the transcripts showed differential expression between the WT and ADAR1E861A fetal liver, with a LogFC≥1.5 and p value <0.05. A profound upregulation of interferon stimulated genes were found to be massively upregulated (up to 11 logFC) in ADAR1E861A fetal liver compared to WT. 6,012 A-to-I RNA editing sites were identified when assessing mismatches in RNA-seq data of WT and ADAR1E861A fetal liver. Conclusions: Our study represents the first detailed analysis of fetal liver transcriptomes and A-to-I RNA editing sites, with biologic replicates, generated by RNA-seq technology. A-to-I RNA editing is the essential function of ADAR1 and is required to suppress interferon signaling to endogenous RNA. Fetal liver mRNA profiles of E12.5 wild type (WT) and ADAR E861A mutant mice were generated by deep sequencing, in triplicate, using Illumina HiSeq 200.