Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

AAV-mediated genome editing is influenced by the formation of R-loops.

ABSTRACT: Recombinant adeno-associated viral vectors (rAAV) hold a natural ability to stimulate homologous recombination (AAV-HR). Moreover, they are also reported to randomly integrate into numerous locations throughout the genome. Here, we describe DNA/RNA immune precipitation sequencing (DRIP-seq) studies in HEPA1-6 cells and whole murine liver to detect genomic r-loops. Through genetic and pharmacological manipulation of r-loops formation, we showed a significant enhancement of AAV-HR. Notably, we were able to detect different levels of r-loops along the Albumin locus. Both in vitro and in vivo experiments showed that the 3’ end of Albumin (high r-loops) is efficiently edited by AAV-HR, whereas the upstream region (low r-loops) did not result in any detectable vector integration. In addition, we were also able to find an interesting correlation between previously reported off-target rAAV integration and r-loop enriched genomic regions. Thus, we conclude that highly transcribed genes accumulate high levels of r-loops, and this could lead to rAAV vector genome integration. These findings may shed light on mechanisms for improving the safety and efficacy of genome editing and may enhance our ability to predict regions most susceptible to insertional mutagenesis with canonical rAAV vectors.

ORGANISM(S): Mus musculus

PROVIDER: GSE261759 | GEO | 2024/05/05

REPOSITORIES: GEO

ACCESS DATA

Json Xml

Dataset's files

Source:

			Action	DRS
		Other

Items per page:

1 - 1 of 1

Similar Datasets

Transcriptomic Analysis Reveals the Inability of Recombinant AAV8 to Activate Human Monocyte-Derived Dendritic Cells

Project description:Recombinant Adeno-Associated Virus (rAAV) is considered as one of the most successful and widely used viral vector for in vivo gene therapy. However, host immune responses to the vector and/or the transgene product remain a major hurdle to successful AAV gene transfer. In contrast to anti-vector adaptive immunity, the initiation of the innate immunity towards rAAV is still poorly understood but is directly dependent on the interaction between the viral vector and innate immune cells. Here, we used a quantitative transcriptomic-based approach to determine the activation of inflammatory and anti-viral pathways after rAAV8-based infection of monocyte-derived Dendritic Cells (moDC) obtained from 12 healthy human donors. We have shown that rAAV8 particles are efficiently internalized, but that this uptake does not induce any detectable transcriptomic change in moDC cells in contrast to an adenoviral infection which upregulates anti-viral pathways. These findings suggest an immunological favorable profile for rAAV8 serotype with regards to in vitro activation of moDC cell model. Transcriptomic analysis of rAAV-infected innate immune cells is a powerful method to determine the ability of the viral vector to be seen by these sensor cells, which remains of great importance to better understand the immunogenicity of rAAV vectors and to design immune-stealth products.

2023-09-12 | GSE228649 | GEO

AAV vector-derived elements integrate into Cas9-generated double strand breaks and disrupt gene transcription

Project description:We previously found that an adeno-associated virus (AAV) vector containing S. aureus Cas9 and a multi-target guide (g)RNA could integrate into the genome and prematurely terminate transcription of Ube3a-ATS, a long non-coding RNA. Here, we assessed the performance of three additional AAV vectors containing S. aureus Cas9 and twenty-five vectors containing N. meningococcus Cas9, all targeting single sites within Ube3a-ATS. We found that none of these single-target gRNA vectors were as effective as multi-target gRNA vectors at reducing Ube3a-ATS expression in neurons. We also developed a new anchored multiplex PCR sequencing (AMP-seq) method and analysis pipeline to quantify the relative frequency of all possible editing events at target sites, including unresolved double-stranded breaks (DSBs) and capture of foreign DNA. We found that integration of AAV was the most frequent editing event (67-89% of all edits) at three different single target sites, far surpassing insertions and deletions (indels). None of the most frequently observed indels was capable of blocking transcription when incorporated into a Ube3a-ATS minigene reporter, whereas two vector derived elements—the polyA and reverse promoter—reduced downstream transcription by up to 50%. Since not all editing events disrupt gene transcription, our findings suggest that the probability that a gene trapping AAV integration event occurs is influenced by which vector-derived element(s) are integrated and by the number of target sites.

2024-10-16 | GSE271068 | GEO

Production of rAAV by plasmid transfection induces antiviral and inflammatory responses in suspension HEK293

Project description:To understand the response of host cells to rAAV vector production via plasmid transfection, samples were collected throughout the course of three 50 L production batches and analyzed by bulk RNA sequencing of polyadenylated transcripts (RNA-seq). Gene ontology analysis determined that upregulated pathways included inflammatory and antiviral responses. Systematic analyses of the cellular transcriptional response to rAAV production indicates that these host cells are not passively supporting vector manufacture, and therefore may illuminate genes and pathways that influence rAAV production, thereby enabling the rational design of next-generation manufacturing platforms to support safe, effective, and affordable AAV-based gene therapies.

2023-02-06 | GSE224405 | GEO

The longitudinal kinetics of AAV5 vector integration profiles and evaluation of clonal expansion in mice

Project description:Recombinant adeno-associated virus (AAV)-based vectors are used clinically for gene transfer and persist as extrachromosomal episomes. A small fraction of vector genomes can integrate into the host genome, but the theoretical risk of tumorigenesis may depend on vector regulatory features. A mouse model was used to investigate long-term kinetics and integration profiles of an AAV serotype 5 (AAV5) vector that mimics key features of valoctocogene roxaparvovec (AAV5-hFVIII-SQ), a gene therapy for severe hemophilia A. The majority (95%) of vector genome reads identified by target enrichment sequencing were derived from episomes, and mean integration frequency was 2.70 (standard deviation, 1.24) integrations per 1000 cells. Longitudinal integration analysis suggested AAV5 vector integrations occur primarily within 1 week, at low frequency, and their abundance was stable over time. Integration profiles were polyclonal, and only 5.46% of integrations had a common integration site order ≥5, suggesting random distributions when looking at a 50-kb genomic window. No integrations were associated with clonal expansion. Integrations were enriched near transcription start sites of genes highly expressed in the liver (P = 1x10−4) and less enriched for genes with low or no liver expression. We found no evidence of tumorigenesis or fibrosis caused by the vector integrations.

2024-02-01 | GSE254503 | GEO

Genotoxicity after adeno-associated virus (AAV) gene therapy is dependent upon dose, treatment age and enhancer-promoter selection

Project description:AAV gene therapy has recently been approved for clinical use and shown to be efficacious and safe in a growing number of clinical trials. However, the safety of AAV as a gene therapy has been challenged by a few studies that documented hepatocellular carcinoma (HCC) after AAV gene delivery in mice. The association between AAV and HCC has been difficult to reconcile and is the subject of intense debate because numerous AAV studies have not reported toxicity. Here, we report a comprehensive study of HCC in a large number of mice following therapeutic AAV gene delivery. Using a sensitive high-throughput integration site-capture technique and global expressional analysis, we found that AAV integration into the Rian locus and the over-expression of a proximal gene, Rtl1, were associated with HCC. In addition, we identify a number of genes with differential expression that maybe useful in the study, diagnosis and treatment of HCC. We demonstrate that AAV vector dose, enhancer-promoter selection, and the timing of gene delivery are the defining factors in AAV-mediated insertional mutagenesis. Our results help explain the AAV-mediated genotoxicity previously observed and have important implications for the design of both safer AAV vectors and gene therapy studies. To investigate the possibility that insertional mutagenesis by AAV contributed to the development of HCC, we collected normal and tumor tissues from adult mouse livers that received AAV injection at a neonatal stage.

2015-01-01 | E-GEOD-57597 | biostudies-arrayexpress

Genotoxicity after adeno-associated virus (AAV) gene therapy is dependent upon dose, treatment age and enhancer-promoter selection (microRNA)

2015-09-01 | E-GEOD-61632 | biostudies-arrayexpress

AAV capsid prioritization in machine-perfused normal and steatotic human livers

Project description:Adeno-associated virus (AAV) vectors generated with five different capsids were intravenously injected into human livers undergoing normothermic machine perfusion (NMP). To assess the tropism of the five AAV vectors in the human livers, single-cell suspensions of hepatocytes and non-parenchymal cells (NPCs) were analyzed by single-cell RNA sequencing (scRNAseq). Differentially expressed genes were identified in AAV vector-transduced hepatocytes and unique cell populations.

2024-11-12 | GSE228000 | GEO

Correlation of antigen expression with epigenetic modifications after rAAV delivery of a human Factor IX variant in mice and rhesus macaques (Tn5 NHP)

Project description:We investigated long-term human coagulation Factor IX expression of a novel variant when delivered into mice and rhesus macaques and compare transduction efficiencies using two different AAV capsids. In hemophilic mice injected with KP1-packaged rAAV expressing the hyperactive FIX variant specific activity plasma levels were 10-fold or 2-fold enhanced when compared to wild-type or Padua huFIX injected mice, respectively. In rhesus macaques AAV-LK03 capsid outperformed AAV-KP1 in terms of antigen expression and liver transduction. Two animals from each group showed sustained low-level huFIX expression at 3 months post-administration, while one animal from each group lost huFIX mRNA and protein expression over time despite comparable vector copies. We investigated if epigenetic differences in the vector episomes could explain this loss of transcription. Cut&Tag analysis revealed lower levels of activating histone marks in the two animals that lost expression. When comparing rAAV genome associated histone modifications in rhesus macaques to those in mice injected with the same vector, the activating histone marks were starkly reduced in macaque-derived episomes. Differential epigenetic marking of AAV genomes may explain different expression profiles in mice and rhesus macaques as well as the wide dose response variation observed in primates in both preclinical and human clinical trials.

2024-03-11 | GSE261046 | GEO

Correlation of antigen expression with epigenetic modifications after rAAV delivery of a human Factor IX variant in mice and rhesus macaques (Tn5 mouse)

2024-03-11 | GSE261045 | GEO

Correlation of antigen expression with epigenetic modifications after rAAV delivery of a human Factor IX variant in mice and rhesus macaques (CnT NHP)

2024-03-11 | GSE261044 | GEO