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PROVIDER: PRJNA865478 | ENA |
REPOSITORIES: ENA
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Project description:Retroviral integration is catalyzed by a tetramer of integrase (IN) assembled on viral DNA ends in a stable complex, known as the intasome. How the intasome interfaces with chromosomal DNA, which exists in the form of nucleosomal arrays, is currently unknown. Here we show that the prototype foamy virus (PFV) intasome is proficient at stable capture of nucleosomes as targets for integration. Single-particle cryo-electron microscopy (EM) reveals a multivalent intasome-nucleosome interface involving both gyres of nucleosomal DNA and one H2A-H2B heterodimer. While the histone octamer remains intact, the DNA is lifted from the surface of the H2A-H2B heterodimer to allow integration at strongly preferred superhelix location (SHL) ±3.5 positions. Amino acid substitutions disrupting these contacts impinge on the ability of the intasome to engage nucleosomes in vitro and redistribute viral integration sites on the genomic scale. Our findings elucidate the molecular basis for nucleosome capture by the viral DNA recombination machinery and the underlying nucleosome plasticity that allows integration. Genomic positions of integration sites of WT and mutant PFV vectors in HT1080 cells were determined using ligation-mediated PCR and next generation sequencing. Integration sites of purified recombinant PFV intasome into deproteinized human genomic DNA were used as a reference dataset.
2015-06-10 | E-GEOD-67730 | biostudies-arrayexpress
Project description:Bacteriophage lambda integration sites
| PRJNA387063 | ENA
Project description:Retroviral integration is catalyzed by a tetramer of integrase (IN) assembled on viral DNA ends in a stable complex, known as the intasome. How the intasome interfaces with chromosomal DNA, which exists in the form of nucleosomal arrays, is currently unknown. Here we show that the prototype foamy virus (PFV) intasome is proficient at stable capture of nucleosomes as targets for integration. Single-particle cryo-electron microscopy (EM) reveals a multivalent intasome-nucleosome interface involving both gyres of nucleosomal DNA and one H2A-H2B heterodimer. While the histone octamer remains intact, the DNA is lifted from the surface of the H2A-H2B heterodimer to allow integration at strongly preferred superhelix location (SHL) ±3.5 positions. Amino acid substitutions disrupting these contacts impinge on the ability of the intasome to engage nucleosomes in vitro and redistribute viral integration sites on the genomic scale. Our findings elucidate the molecular basis for nucleosome capture by the viral DNA recombination machinery and the underlying nucleosome plasticity that allows integration.
2015-06-10 | GSE67730 | GEO
Project description:Exploiting the full potential of insertional mutagenesis screens with retroviruses and transposons requires methods for distinguishing clonal from subclonal insertion events within heterogeneous tumor cell populations. Current protocols, based on ligation mediated PCR, depend on endonuclease based fragmentation of genomic DNA, resulting in strong biases in amplification and sequencing due to a fixed product sizes of the amplicon. We have developed a method called shear-splink, which enables the semi-quantitative high-throughput sequence analysis of insertional mutations, enabling us to count the number of cells harboring a given integration, within a heterogeneous sample. The shear-splink method enriches for (sub)clonal integrations, thereby reducing the contribution of irrelevant passenger mutations normally hampering a reliable identification of common integration sites. Additionally, this improvement allows us to identify genetic interactions between affected genes, co-occurring mutations and to study acquired resistance mechanisms both in vivo and in vitro. Sequencing of retrovrial integration sites by LM-PCR. The associated manuscript describes a new method to quantitatively determine retrovrial integration sites using an improved ligation-mediated PCR approach and subsequent 454 pyrosequencing. [GSM562151 to GSM562159]: Sequence data from different mixtures of 2 different cell lines (called AE6 and BB12) which are processed without a restriction enzyme. These cell lines are derived from an MMTV induced mammary tumor, for which we amplify the MMTV integration sites using a ligation-mediated PCR setup. We mixed these 2 cell lines, both with a different integration spectrum, to determine whether our amplification and sequencing protocol is quantitative, meaning that the coverage per integration site is decreasing upon a further dilution of the sample. [GSM641935 to GSM641950]: Unique Sleeping beauty induced lymphoma specimens (spleen) obtained from a cohort of 16 wild-type mice with the 129P2/C57BL/6J mixed background. [GSM776576 to GSM776956]: The 379 submitted specimens are originating from 127 unique leukemia/lymphoma samples, processed using 3 different techniques in order to identify Sleeping Beauty integration sites. We compared restriction enzyme based LM-PCR (RE-splink) with shearing based LM-PCR (shear-splink) on 127 unique Sleeping Beauty (SB) induced leukemia's/lymphomas. All sequence data generated by the 454 sequencing platform are submitted to GEO, including the final output of our sequence analysis pipeline (in bed format; see Supplementary files linked below). Previous submissions contained similar sequence information (integration sites of viruses or transposons driving tumorigenesis) and are all part of the same manuscript.
2011-08-11 | E-GEOD-22657 | biostudies-arrayexpress
Project description:Retroviruses integrate their genomes into the genomes of infected host cells and form a genetic platform for stable gene expression. Epigenetic silencing can, however, hamper the expression of integrated provirus. As gammaretroviruses (γRVs) preferentially integrate into sites of active promoters and enhancers, the high expression activity of γRVs can be attributed to the integration preference. Long terminal repeats (LTRs) of some γRVs were shown to act as potent promoters for gene expression. Here, we investigate the capacity of different γRV LTRs to drive stable expression inside a non-preferred epigenomic environment using MLV-derived BET-independent (Bin) vectors. We demonstrate that different γRV LTRs are either rapidly silenced or long-term active with active proviral population prevailing under normal and retargeted integration.
2024-06-17 | GSE269015 | GEO
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
Project description:BORIS/CTCFL epigenetically reprograms clustered CTCF binding sites into alternative transcriptional start sites.
| PRJNA853953 | ENA
Project description:MLV integration sites in human K562 cells
| PRJNA188712 | ENA