Project description:Distinct integration patterns of different retroviruses have puzzled virologists for over 20 years. The viral integrase (IN), as part of the intasome complex, docks onto the target DNA (tDNA) and catalyzes the insertion of the viral genome into the host chromatin. We identified retroviral IN amino acids directly contacting tDNA bases and affecting the local integration site sequence biases. These residues also determine the propensity of the virus to integrate into flexible tDNA sequences. Remarkably, natural polymorphisms INS119G and INR231G retarget viral integration away from gene dense regions, without affecting the interaction with the lentiviral tethering cofactor LEDGF/p75 (PSIP1). Precisely these variants were associated with rapid disease progression in a chronic HIV-1 subtype C infection cohort. These findings link integration site selection to virulence and viral evolution but also to the host immune response and antiretroviral therapy, since HIV-1 IN119 is under selection by HLA alleles and integrase inhibitors. LEDGF/p75 (PSIP1) ChIP-Seq using A300-848 antibody (recognizes p75 isoform) and input control in primary CD4+ T-cells
Project description:We report the development of a novel method called EpiVIA (https://github.com/VahediLab/epiVIA) for the joint profiling of the chromatin accessibility and lentiviral integration site analysis at the population and single-cell levels. We validate our technique in clonal cells with previously defined integration sites and further demonstrate the ability to measure lentiviral integration sites and chromatin accessibility of host and viral genomes at the single-cell resolution in CAR-T cells. We anticipate that EpiVIA will enable the single-cell deconstruction of gene regulation during CAR-T therapy, leading to the discovery of cellular factors associated with durable treatment.
Project description:We report the development of a novel method called EpiVIA (https://github.com/VahediLab/epiVIA) for the joint profiling of the chromatin accessibility and lentiviral integration site analysis at the population and single-cell levels. We validate our technique in clonal cells with previously defined integration sites and further demonstrate the ability to measure lentiviral integration sites and chromatin accessibility of host and viral genomes at the single-cell resolution in CAR-T cells. We anticipate that EpiVIA will enable the single-cell deconstruction of gene regulation during CAR-T therapy, leading to the discovery of cellular factors associated with durable treatment.
Project description:CRISPR/Cas9 has revolutionized genome editing with broad therapeutic applications, yet its repair patterns in vivo remain poorly understood. Here, we systematically profile CRISPR/Cas9 editing outcomes at 95 loci using our established CRISPR/Cas9/AAV9-sgRNA system in skeletal muscle stem cells (MuSCs). Through comprehensive characterization of the repair outcomes, our findings demonstrate that the general rules governing CRISPR/Cas9-mediated editing in vivo largely align with those observed in vitro. Additional to the anticipated small editing indels such as MMEJ mediated deletions and NHEJ mediated templated insertions, we uncover a prevalent occurrence of large on-target modifications, including large deletions (LDs) characterized by microhomology (MH) and large insertions (LIs). Notably, the LIs comprise not only exogenous AAV vector integrations but also endogenous genomic DNA fragments (Endo-LIs). Endo-LIs preferentially originate from active genomic regions, with their integration shaped by three-dimensional chromatin architecture. By disrupting key components of the NHEJ and MMEJ repair pathways in vivo, we identify their distinct roles in regulating the large on-target modifications. Together, our work systematically profiles the CRISPR/Cas9 repair outcomes in vivo and offers valuable guidance for improving the safety of CRISPR/Cas9-based gene therapies.
Project description:CRISPR/Cas9 has revolutionized genome editing with broad therapeutic applications, yet its repair patterns in vivo remain poorly understood. Here, we systematically profile CRISPR/Cas9 editing outcomes at 95 loci using our established CRISPR/Cas9/AAV9-sgRNA system in skeletal muscle stem cells (MuSCs). Through comprehensive characterization of the repair outcomes, our findings demonstrate that the general rules governing CRISPR/Cas9-mediated editing in vivo largely align with those observed in vitro. Additional to the anticipated small editing indels such as MMEJ mediated deletions and NHEJ mediated templated insertions, we uncover a prevalent occurrence of large on-target modifications, including large deletions (LDs) characterized by microhomology (MH) and large insertions (LIs). Notably, the LIs comprise not only exogenous AAV vector integrations but also endogenous genomic DNA fragments (Endo-LIs). Endo-LIs preferentially originate from active genomic regions, with their integration shaped by three-dimensional chromatin architecture. By disrupting key components of the NHEJ and MMEJ repair pathways in vivo, we identify their distinct roles in regulating the large on-target modifications. Together, our work systematically profiles the CRISPR/Cas9 repair outcomes in vivo and offers valuable guidance for improving the safety of CRISPR/Cas9-based gene therapies.
Project description:CRISPR/Cas9 has revolutionized genome editing with broad therapeutic applications, yet its repair patterns in vivo remain poorly understood. Here, we systematically profile CRISPR/Cas9 editing outcomes at 95 loci using our established CRISPR/Cas9/AAV9-sgRNA system in skeletal muscle stem cells (MuSCs). Through comprehensive characterization of the repair outcomes, our findings demonstrate that the general rules governing CRISPR/Cas9-mediated editing in vivo largely align with those observed in vitro. Additional to the anticipated small editing indels such as MMEJ mediated deletions and NHEJ mediated templated insertions, we uncover a prevalent occurrence of large on-target modifications, including large deletions (LDs) characterized by microhomology (MH) and large insertions (LIs). Notably, the LIs comprise not only exogenous AAV vector integrations but also endogenous genomic DNA fragments (Endo-LIs). Endo-LIs preferentially originate from active genomic regions, with their integration shaped by three-dimensional chromatin architecture. By disrupting key components of the NHEJ and MMEJ repair pathways in vivo, we identify their distinct roles in regulating the large on-target modifications. Together, our work systematically profiles the CRISPR/Cas9 repair outcomes in vivo and offers valuable guidance for improving the safety of CRISPR/Cas9-based gene therapies.
Project description:Distinct integration patterns of different retroviruses have puzzled virologists for over 20 years. The viral integrase (IN), as part of the intasome complex, docks onto the target DNA (tDNA) and catalyzes the insertion of the viral genome into the host chromatin. We identified retroviral IN amino acids directly contacting tDNA bases and affecting the local integration site sequence biases. These residues also determine the propensity of the virus to integrate into flexible tDNA sequences. Remarkably, natural polymorphisms INS119G and INR231G retarget viral integration away from gene dense regions, without affecting the interaction with the lentiviral tethering cofactor LEDGF/p75 (PSIP1). Precisely these variants were associated with rapid disease progression in a chronic HIV-1 subtype C infection cohort. These findings link integration site selection to virulence and viral evolution but also to the host immune response and antiretroviral therapy, since HIV-1 IN119 is under selection by HLA alleles and integrase inhibitors.
2015-01-26 | GSE61003 | GEO
Project description:PRISM-Seq: An Ultra-sensitive Sequencing Approach For Mapping Lentiviral Integration Sites
Project description:DNA integration is a defining step in the retroviral life cycle and the basis of stable gene transfer in retrovirus-based gene therapy. Previous studies of integration by HIV-based vectors have shown that integration is not random, but favored in active transcription units. Studies to date have focused on HIV integration in dividing cells, leaving open the question of whether integration target site selection might differ in nondividing cells. According to one idea, division of the host cell might be required for favored integration in transcription units, possibly as a result of chromatin remodeling during DNA replication. Here we have investigated this issue by comparing integration in dividing IMR-90 primary lung fibroblasts to integration in nondividing IMR-90 cells arrested in G1 by serum starvation and contact inhibition. We identified several differences in integration site selection in arrested versus dividing cells, including the frequency of integration in transcription units and in gene-rich regions. However, integration in nondividing cells was in fact more favored in transcription units, contrary to the idea that cell division was important for this bias. These data provide the first view of lentiviral integration in nondividing cells and help constrain models for the mechanism of favored integration in genes. Keywords: comparative genomic analysis, dividing versus non-dividing cells.
Project description:A deeper understanding of the biology of therapy resistant cells is important for the development of optimal therapeutic strategies to attain complete cure of leukemia. Here we compared chromatin accessibility of CML patient cells treated with Imatinib vs untreated cells and column enriched deep-quiescent LI (leukemia initiator) cells. ICG-001 treatment of LIs suggested increased differentiation of LIs.