Project description:The activity of cardiomyocyte and control enhancers was assessed in mouse cardiomyocytes, using two assay formats: a Tnni1 genomically integrated MPRA and AAV-based episomal MPRAs with various minimal promoters.
Project description:CRISPR-Cas9 delivery by AAV holds promise for gene therapy but faces critical barriers due to its potential immunogenicity and limited payload capacity. Here, we demonstrate genome engineering in postnatal mice using AAV-split-Cas9, a multi-functional platform customizable for genome-editing, transcriptional regulation, and other previously impracticable AAV-CRISPR-Cas9 applications. We identify crucial parameters that impact efficacy and clinical translation of our platform, including viral biodistribution, editing efficiencies in various organs, antigenicity, immunological reactions, and physiological outcomes. These results reveal that AAV-CRISPR-Cas9 evokes host responses with distinct cellular and molecular signatures, but unlike alternative delivery methods, does not induce detectable cellular damage in vivo. Our study provides a foundation for developing effective genome therapeutics mRNA-Seq from muscles (9 samples; 3 mice x 3 conditions) and lymph nodes (9 samples; 3 mice x 3 conditions).
Project description:Adeno-associated virus (AAV) vectors are important delivery platforms for therapeutic genome editing but are severely constrained by cargo limits, especially for large effectors like Cas9s. Simultaneous delivery of multiple vectors can limit dose and efficacy and increase safety risks. The use of compact effectors has enabled single-AAV delivery of Cas9s with 1-3 guides for edits that use end-joining repair pathways, but many precise edits that correct disease-causing mutations in vivo require homology-directed repair (HDR) templates. Here, we describe single-vector, ~4.8-kb AAV platforms that express Nme2Cas9 and either two sgRNAs to produce segmental deletions, or a single sgRNA with an HDR template. We also examine the utility of Nme2Cas9 target sites in the vector for self-inactivation. We demonstrate that these platforms can effectively treat two disease models [type I hereditary tyrosinemia (HT-I) and mucopolysaccharidosis type I (MPS-I)] in mice. These results will enable single-vector AAVs to achieve diverse therapeutic genome editing outcomes.
Project description:CRISPR-Cas9 delivery by AAV holds promise for gene therapy but faces critical barriers due to its potential immunogenicity and limited payload capacity. Here, we demonstrate genome engineering in postnatal mice using AAV-split-Cas9, a multi-functional platform customizable for genome-editing, transcriptional regulation, and other previously impracticable AAV-CRISPR-Cas9 applications. We identify crucial parameters that impact efficacy and clinical translation of our platform, including viral biodistribution, editing efficiencies in various organs, antigenicity, immunological reactions, and physiological outcomes. These results reveal that AAV-CRISPR-Cas9 evokes host responses with distinct cellular and molecular signatures, but unlike alternative delivery methods, does not induce detectable cellular damage in vivo. Our study provides a foundation for developing effective genome therapeutics
Project description:To investigate if the truncated PE can be dilivered by dual AAV8 vectors for in vivo prime editing. We injected the dual AAV8 into 10-week-old C57BL/6J mice . Livers were isolated 4 weeks after injection and next generation sequencing showed an average of 1.4% and 5.4% precise prime editing with the low and high AAV doses, respectively (Figure 4D ). This demonstrates that PECO-Mini can be efficiently delivered by dual AAVs for in vivo prime editing.
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:Adenosine-to-inosine RNA base editing is a strategy developed to safely manipulate genetic information at the RNA level. Particularly promising for clinical implementation is the use of the ubiquitously expressed endogenous editing enzyme ADAR (adenosine deaminase acting on RNA) with tailored guide RNAs. However, the precision of editing could be compromised by global off-target events that can potentially occur throughout the transcriptome. In this study, we introduce a novel circular CLUSTER guide RNA design that recruits endogenous ADAR in vivo. The goals of the whole transcriptome sequencing experiment were to evaluate the A-to-G RNA editing index and the global editing precision of this novel design. To achieve this, Rett syndrome mice harboring a Mecp2 W104Amber mutation were treated either with a circular CLUSTER guide RNA targeting the mutant Mecp2 transcript or a scrambled and thus non-targeting control guide RNA. Both the targeting and the non-targeting guide RNA were encoded as AAV and delivered via retro-orbital injection of 4x10^12 viral genomes per mouse. The used AAV serotype PHP.eB allows cargo delivery to the mouse brain after systemic administration. Four weeks after injection the thalamus was isolated for NGS analysis. Whole transcriptome sequencing showed that the A-to-G RNA editing index was unaffected by treatment with the targeting guide RNA compared to the scrambled non-targeting control. We were unable to identify any global off-target events, excluding mouse to mouse variability, which suggests a very high precision of our approach on the transcriptome-wide level. Harnessing endogenous ADAR with permanent, AAV-driven CLUSTER guide RNAs in the CNS is an important next step towards the development of novel drug modalities that fight neurological diseases.
Project description:Large genes including several CRISPR-Cas modules, such as gene activators (CRISPRa), require dual adeno-associated viral (AAV) vectors for efficient in vivo delivery and expression. Current dual AAV vector approaches have important limitations, e.g., low reconstitution efficiency, production of alien proteins, or low flexibility in split site selection. Here, we present a dual AAV vector technology based on reconstitution via mRNA trans-splicing (REVeRT). REVeRT is flexible in split site selection and can efficiently reconstitute different split genes in numerous in vitro models, in human organoids and in vivo. Furthermore, REVeRT can functionally reconstitute a CRISPRa module targeting genes in various mouse tissues and organs in single or multiplexed approaches upon different routes of administration. Finally, supplementation of ABCA4 (6.8 kb) via REVeRT improves retinal degeneration and function in a mouse model of inherited blindness. Due to its flexibility and efficiency REVeRT harbors great potential for basic research and clinical applications.
Project description:Chromosomal rearrangements including large DNA-fragment inversions, deletions, and duplications by Cas9 with paired sgRNAs are important to investigate structural genome variations and developmental gene regulation, but little is known about the underlying mechanism. Here we report that disrupting CtIP or FANCD2, which is thought to function in NHEJ, enhances precise DNA-fragment deletion. In addition, by analyzing the inserted nucleotides at the junctions of DNA-fragment deletions, inversions, duplications, and characterizing the cleaved products, we find that Cas9 endonucleolytically cleaves the noncomplementary strand with a flexible scissile profile upstream of -3 position of the PAM site in vivo and in vitro, generating overhanged DSB ends. Moreover, we find that engineered Cas9 nucleases have distinct cleavage profiles. Finally, Cas9-mediated nucleotide insertions are nonrandom and are equal to the combined sequences upstream of both PAM sites with predicted frequencies. Thus, precise and predictable DNA-fragment editing could be achieved by perturbing DNA repair genes and using appropriate PAM configurations. These findings have important implications regarding 3D chromatin folding and enhancer insulation during gene regulation.