Project description:Adenine and cytosine base editors (ABEs and CBEs) represent a new genome editing technology that allows the programmable installation of A-to-G or C-to-T alterations on DNA. We engineered Streptococcus pyogenes Cas9-based adenine and cytosine base editor (SpACE) that enables efficient simultaneous introduction of A-to-G and C-to-T substitutions in the same base editing window on DNA.
Project description:Current base editors use DNA deaminases, including cytidine deaminase in cytidine base editor (CBE) or adenine deaminase in adenine base editor (ABE), to facilitate transition nucleotide substitutions. Combining CBE or ABE with glycosylase enzymes can induce limited transversion mutations. Nonetheless, a critical demand remains for base editors capable of generating alternative mutation types, such as T>G corrections. In this study, we leveraged pre-trained protein language models to optimize a uracil-N-glycosylase (UNG) variant with altered specificity for thymines (eTDG). Notably, after two rounds of testing fewer than 50 top-ranking variants, more than 50% exhibited over 1.5-fold enhancement in enzymatic activities. When eTDG was fused with nCas9, it induced programmable T-to-S (G/C) substitutions and corrected db/db diabetic mutation in mice (up to 55%). Our findings not only establish orthogonal strategies for developing novel base editors, but also demonstrate the capacities of protein language models for optimizing enzymes without extensive task-specific training data.
Project description:We show that delivering the mitochondrial base editor DdCBEs via AAV transduction of somatic cells efficiently produces precise base editing of the intended region.
Project description:We used an adenine base editor to target the translation start site and mRNA splicing site of Camk2d in order to knock out CaMKIIδ. We found that editing the 5' splice site of intron 7 can lead to premature translation termination, effectively knocking out CaMKIIδ.
Project description:We used an adenine base editor to target the translation start site and mRNA splicing site of Camk2d in order to knock out CaMKIIδ. We found that editing the 5' splice site of intron 7 can lead to premature translation termination, effectively knocking out CaMKIIδ.
Project description:Techniques for exclusion of exons from mature transcripts have been applied as gene therapies for treating many different diseases. Since exon skipping has been traditionally accomplished using technologies that have a transient effect, it is particularly important to develop new techniques that enable permanent exon skipping. We have recently demonstrated that this can be accomplished using cytidine base editors for permanently disabling the splice acceptor of target exons. We now demonstrate the application of adenine-deaminase base editors to disrupt the conserved adenosine within splice acceptor sites for programmable exon skipping. We also demonstrate that by altering the amino acid sequence of the linker between the adenosine deaminase domain and the Cas9 nickase or by coupling the adenine base editor with a uracil glycosylase inhibitor, the DNA editing efficiency and exon skipping rates improve significantly. Finally, we developed a split base editor architecture compatible with adeno-associated viral packaging. Collectively, these results represent significant progress towards permanent in vivo exon skipping through base editing and, ultimately, a new modality of gene therapy for the treatment of genetic diseases.
2019-09-12 | GSE120125 | GEO
Project description:Base editing analysis of muscles from adenine base editor-treated DMD mice.
Project description:RNA editing can be a promising therapeutic approach. However, ectopic expression of RNA editing enzymes was found to trigger off-target editing, and the recruitment of endogenous adenosine deaminase acting on RNA (ADAR) suffers from low efficiency and fluctuating ADAR expression. Here, we identified ADAR inhibitors (ADIs) that suppressed the activity of the fused ADAR2 deaminase domain (ADAR2DD). Using ADI, we developed an RNA transformer adenine base editor (RtABE) with both high specificity and high efficiency. With the fusion of ADI to ADAR2DD, RtABE remains inactive until it binds its target site. After binding to the target site, ADI is cleaved from ADAR2DD and RtABE becomes active. RtABE induced efficient on-target editing in various cells with different ADAR expression levels. Delivering RtABE via an adeno-associated virus enabled up to a 45% RNA correction rate in Hurler syndrome mice with no significant off-target editing, and -L-iduronidase activity was restored. RtABE is a highly specific and efficient RNA editing system with broad applicability.