Project description:Primary mitochondrial disorders are most often caused by deleterious mutations in the mtDNA. Here, we harnessed a mitochondrial base editor, DdCBE, to introduce a compensatory edit (m.5081G→A) in a mouse model that carries the pathological m.5024C→T mutation in the mitochondrial tRNAAla gene. For this, the DdCBE gene construct was packaged in recombinant AAV9 and systemically injected into mice. We found that total mt-tRNAAla levels, which are drastically reduced by the mutation, are restored by the m.5081G→A edit in a dose-dependent manner. However, an excessive expression of DdCBE also induces extensive mtDNA off-target editing, counteracting this positive outcome. To address this, we optimized the dosage to maximize the amount of compensatory edit generated with minimal off-target editing. These results show that mitochondrial base editors are promising candidates for gene therapy for mitochondrial disorders, but their expression need to be carefully controlled.
Project description:Colon from mouse with genetic background VBPN was extracted and wild-type organoid culture was created. Afterwards, the organoids were treated with 4-OHT and cancerous organoids with BPN mutations were created. Subsequently, 2 Apc and 2 Rnf43 cell lines were created via CRIPSR knock-out. Additionally, Ctnnb1 gene was edited via CRISPR base editing and the edit S33F was created. Finally, also non-nargeting conrotl cell lines for conventional knock-out (NT) and base editing (NTBE) were generated. From these cell lines RNA-seq was performed.
Project description:We use base editing to eliminate the CaMKII-delta, a major driver of heart disease. We found that insertion of microRNA122 target sequence (miR122 TS) in the 3' UTR of the vector eliminates editing in the liver, in combination with heart-specific promoters to specifically edit in heart.
Project description:To develop a new therapeutic strategy for cardiac ischemia/reperfusion injury, we ablated the oxidative activation site of CaMKIIδ in the heart using CRISPR-Cas9 adenine base editing technology. Adult C57Bl6 mice were subjected to control surgery (IR-Sham, 3 biological replicates) or ischemia/reperfusion injury with either no injection (IR, 3 biological replicates), injection of a control virus (IR-Virus control, 3 biological replicates) or injection of a functional CaMKIIδ editing system (IR-Edit, 4 biological replicates). Five weeks after the surgery, hearts were harvested for RNA isolation and subsequent bulk RNA sequencing and gene expression profiling analysis.
Project description:CRISPR-enabled genetic screening is a powerful tool to discover genes that control T cell function and has nominated candidate target genes for immunotherapies1–6. However, new approaches are required to probe specific nucleotide sequences within key genes. Systematic mutagenesis in primary human T cells could discover alleles that tune specific phenotypes. DNA base editors are powerful tools to introduce targeted mutations with high efficiency7,8. Here, we develop a large-scale base editing mutagenesis platform with the goal of pinpointing nucleotides encoding amino acid residues that tune primary human T cell activation responses. We generated a library of ~117,000 sgRNAs targeting base editors to protein coding sites across 385 genes implicated in T cell function and systematically identified protein domains and specific amino acid residues that regulate T cell activation and cytokine production. We discovered a broad spectrum of alleles with variants encoding critical residues (in PIK3CD, VAV1, LCP2, PLCG1 and DGKZ and others), comprising both gain-of-function and loss-of-function mutations. We validated the functional effects of diverse alleles and further demonstrated that base edit hits could positively and negatively tune T cell cytotoxic function. Finally, higher-resolution screening using a base editor with relaxed PAM requirements9 (NG versus NGG) revealed specific structural domains and protein-protein interaction sites that can be targeted to tune T cell functions. Base editing screens in primary immune cells provide biochemical insights with potential to accelerate immunotherapy design.
Project description:Duchenne muscular dystrophy is an X-linked monogenic disease caused by mutations in the dystrophin gene (DMD) and characterized by progressive muscle weakness leading to loss of ambulation and significantly decreased life expectancy. Since the current standard of care for Duchenne muscular dystrophy is to merely treat symptoms, there is a dire need for novel treatment modalities that can correct the underlying genetic mutations. While several gene replacement therapies are being explored in clinical trials, one emerging approach that can directly correct mutations in genomic DNA is base editing. We have recently developed CRISPR-SKIP, a base editing strategy to induce permanent exon skipping by introducing C>T or A>G mutations at splice acceptors in genomic DNA, which can be utilized therapeutically to recover dystrophin expression when a genomic deletion leads to an out-of-frame DMD transcript. We now demonstrate that CRISPR-SKIP can be adapted to correct some forms of Duchenne muscular dystrophy by disrupting the splice acceptor in human DMD exon 45 with high efficiency, which enables open reading frame recovery and restoration of dystrophin expression. We also demonstrate that AAV-delivered split-intein base editors edit the splice acceptor of DMD exon 45 in cultured human cells and in vivo, highlighting the therapeutic potential of this strategy.
Project description:Endogenous Uridine-rich small nuclear RNAs (U snRNAs) form RNA-protein complexes to process eukaryotic pre-mRNA into mRNA. Previous studies have demonstrated programmable U snRNA guide-targeted exon inclusion and exclusion. We investigated whether snRNAs can also enhance RNA base editing over state-of-the-art RNA-targeting technologies in human cells. Compared to adenosine deaminase acting on RNA (ADAR)-recruiting circular RNAs, we find that guided A>I snRNAs consistently increase adenosine-to-inosine editing for higher exon count genes, perturb substantially fewer off-target genes, and localize more persistently to the nucleus where ADAR is expressed. A>I snRNAs also more efficiently edit lncRNAs and pre-mRNA 3′ splice sites to promote splicing changes. Finally, snRNA-H/ACA box snoRNA fusions (U>Ψ snRNAs) increase targeted RNA pseudouridylation without DKC1 overexpression, facilitating improved CFTR rescue from nonsense-mediated mRNA decay in a Cystic fibrosis human bronchial epithelial cell model. Our results advance the endogenous protein-mediated RNA base editing toolbox and RNA-targeting technologies to treat genetic diseases.
Project description:A cell’s fate is shaped by its inherited state, or lineage, and the ever-shifting context of its environment. CRISPR-based recording technologies are a promising solution to map the importance of lineage, yet challenges remain regarding single-cell recovery, engineering complexity, and scale. Here, we introduce BASELINE, which uses base editing to generate high-resolution lineage trees in conjunction with single-cell profiling. BASELINE uses the Cas12a adenine base editor to irreversibly edit nucleotides within 50 synthetic target sites, which are integrated multiple times into a cell’s genome. We show that BASELINE accumulates lineage-specific marks over a wide range of biologically relevant intervals, recording more than 4300 bits of information in a model of pancreatic cancer. Single-cell sequencing reveals high-fidelity capture of these lineage recorders, recovering lineage reconstructions up to 46 cell-divisions deep, within the estimated range of mammalian development. We expect BASELINE to be applicable to various lineage-tracing projects in development and disease, especially in which cellular engineering makes small, more distributed systems challenging.