HIV-1 LTR targeting 4C-seq
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA956820 | ENA |
REPOSITORIES: ENA
Similar Datasets
Project description:HIV-1 integration introduces ectopic transcription factor binding sites into host chromatin. We postulate that the integrated provirus serves as an ectopic enhancer that recruits additional transcriptional factors to the integration locus, increases chromatin accessibility, changes 3D chromatin interactions, and enhances both retroviral and host gene expression. We used 4 well-characterized HIV-1-infected cell line clones having unique integration sites and low to high levels of HIV-1 expression. Using single-cell DOGMA-seq, which captured the heterogeneity of HIV-1 expression and host chromatin accessibility, we found that HIV-1 transcription correlated with HIV-1 accessibility and host chromatin accessibility. HIV-1 integration increased local host chromatin accessibility within ~5–30 kb distance. CRISPRa and CRISPRi-mediated HIV-1 promoter activation and inhibition confirmed integration site-dependent HIV-1-driven changes of host chromatin accessibility. HIV-1 did not drive chromatin confirmation changes at the genomic level (by Hi-C) or the enhancer connectome (by H3K27Ac HiChIP). Using 4C-seq to interrogate HIV-1-chromatin interactions, we found that HIV-1 interacted with host chromatin ~100–300 kb from the integration site. By identifying chromatin regions having both increased transcription factor activity (by ATAC-seq) and HIV-1-chromtain interaction (by 4C-seq), we identified enrichment of ETS, RUNT, STAT, and ZNF transcription factor binding that may mediate HIV-1-host chromatin interactions. Our study found that HIV-1 promoter activity increased host chromatin accessibility, increased HIV-1-host chromatin interactions in an integration site dependent manner, within the existing chromatin boundaries without impacting broader host chromatin structure.
2023-05-01 | GSE229926 | GEO
Project description:A major pharmacological strategy toward HIV cure aims to reverse latency in infected cells as a first step leading to their elimination. While the unbiased identification of molecular targets physically associated with the latent HIV-1 provirus would be highly valuable to unravel the molecular determinants of HIV-1 transcriptional repression and latency reversal, due to technical limitations, this has been challenging. Here we use a dCas9 targeted chromatin and histone enrichment strategy coupled to mass spectrometry (Catchet-MS) to probe the differential protein composition of the latent and activated HIV-1 5'LTR. Catchet-MS identified known and novel latent 5’LTR-associated host factors. Among these, IKZF1 is a novel HIV-1 transcriptional repressor, required for Polycomb Repressive Complex 2 recruitment to the LTR. We find the clinically advanced thalidomide analogue iberdomide, and the FDA approved analogues lenalidomide and pomalidomide, to be novel LRAs that, by targeting IKZF1 for degradation, reverse HIV-1 latency in CD4+T-cells isolated from virally suppressed people living with HIV-1.
2022-02-06 | GSE196059 | GEO
Project description:The three-dimensional structure of the genome is a regulator of transcription and cell function; HIV-1 infection can influence host cell function, but the degree to which this is mediated through changes to host chromatin architecture is unclear. We interrogated genome-wide chromatin organization and the structure of chromatin around latently infected HIV-1 integration sites using Hi-C and ATAC-seq and combined these data with RNA transcriptional analysis of the provirus and neighboring genes in HIV-inducible cellular models. We found chromatin interaction networks around integrated HIV-1 are predominantly preserved with respect to uninfected cells, proving the lack of an obligate association between latent integration and major chromatin remodeling. Instead, we find that induction of proviral transcription may lead to local changes in chromatin accessibility downstream from the 3’ LTR, demonstrating that HIV-1 can alter local cellular chromatin structure post-integration. Using long-read Nanopore RNA-seq, we interrogated the local host and HIV-1 transcriptomes and observed that 1-5% of HIV-1 transcripts initiated at the 5’ LTR promoter extended into the flanking cellular genome, generating chimeric virus-host RNAs. Thus, integration leading to latency (and provirus activation) may not lead to obligate global chromatin rearrangements; we also observed, previously unreported, novel changes in chromatin accessibility during HIV-1 transcription.
2022-08-26 | GSE189178 | GEO
Project description:HIV-1 infected patients virally suppressed by antiviral treatment harbor a persistent reservoir of replication competent latent HIV-1 infected cells, which constitute the main roadblock to a cure. A main strategy for HIV cure aims to stimulate viral gene expression in latently infected cells so that they can be cleared. Crucial for the design of drugs referred to as “latency-reversing agents” (LRAs) is the identification of molecular targets for latency reversal. The regulatory factors physically associated with and repressing the latent HIV-1 promoter or 5’LTR would provide ideal putative molecular targets for latency reversal. However, due to technical limitations, the comprehensive and unbiased identification of host proteins associated with the latent or active integrated HIV LTR in infected cells not been possible. Here we use dCas9 targeted chromatin and histone enrichment strategy coupled to mass spectrometry (Catchet-MS), to purify the locus-associated dCas9 bait, guided downstream of the HIV-1 transcriptional start site (TSS) in latent and activated HIV-1 infected T cells to identify the 5’LTR bound latent and active regulatory complexes. Catchet-MS identified both previously described as well as novel host factors distinctly associated with the latent versus transcriptionally active HIV-1 5’LTR. Within the identified factors we find the transcription factor IKZF1 to be a novel repressor of the HIV-1 promoter required for maintenance of latency, and thus a molecular target for latency reversal. Finally, we identify the FDA approved drug, Iberdomide, which targets IKZF1 for degradation to be a novel LRA, which reversed latency in latent ex vivo HIV-1 infected primary CD4+ T cells and in cells isolated from HIV-1 infected, aviremic participants.
2022-05-31 | PXD032975 | Pride
Project description:The restructuring of chromatin architecture following lentiviral integration is not well elucidated. We jointly interrogate (HIV-distal & -local) chromatin organization (via Hi-C & ATAC-seq) and the RNA landscape around defined sites of proviral integration using HIV-inducible cellular models. We report chromatin interaction networks and nuclear ultrastructure around integrated HIV-1 are predominantly preserved, suggesting HIV integration does not induce large scale remodeling of cellular chromatin. Instead, we find that induction of proviral transcription leads to stark local changes in nucleosome organization with chromatin accessibility increasing at the intergenic junction between the HIV-1 3’ LTR and flanking cellular genome. This result suggests subtle changes in chromatin structure may be mediating proviral activation. Using long-read Nanopore RNA-seq, we interrogate the local host & HIV transcriptomes, observing a small fraction of HIV-1 transcripts are chimeric read-through products, where transcription initiates at the HIV-1 5’ LTR promoter and continues extensively into the flanking cellular genome. Despite provirus-driven read-through, HIV-1 appears to have only a modest effect on the local transcriptional environment. The changes in chromatin accessibility and read-through at activated proviruses closely resembles lytic Herpes simplex virus type 1 (HSV-1) induced cellular chromatin reprogramming. We propose chromatin “opening” at the 3’ LTR HIV-host junction is important for sustained proviral activity, and overall, HIV proviruses do not significantly alter local host transcription and chromatin structure. Our studies provide the first in-depth integrative investigation of 3D chromatin organization, nucleosome density, and HIV-host transcriptomes at HIV-host genic boundaries.
2021-10-26 | GSE184345 | GEO
Project description:HIV-1 latency results from a combination of tightly regulated molecular processes that act at distinct steps of HIV-1 gene expression. In an effort to elucidate the molecular players that govern viral latency, we previously performed a dCas9 chromatin immunoprecipitation coupled with mass spectrometry (Catchet-MS) and identified proteins bound differentially to the latent LTR that putatively promote HIV-1 latency. Here we characterize the Catchet-MS identified PCI domain-containing 2 (PCID2) protein to play a dual role in promoting HIV-1 latency by enforcing both HIV-1 transcription repression as well as post-transcriptional blocks. PCID2 bound the latent HIV-1 LTR and repressed transcription initiation during latency. Depletion of PCID2 remodeled the chromatin landscape at the HIV-1 promoter and resulted in transcriptional activation and reversal of latency. Immunoprecipitation coupled to Mass Spectrometry identified the PCID2 interacting proteins to include members of the spliceosome and other splicing regulators, including negative regulators of viral RNA alternative splicing. PCID2 depletion resulted in over-splicing of intron-containing HIV-1 RNA and mis-regulated expression of vRNA splice variants. Finally, consistent with its role in NXF1-mediated nascent RNA nucleocytoplasmic export as part of the TREX2 complex, PCID2 modulates export of completely spliced vRNA. In summary, we demonstrate that PCID2 is a previously unidentified factor involved in HIV-1 latency regulation which plays a dual role in blocking HIV-1 gene expression by acting on transcription initiation as well as viral RNA processing.
2024-06-16 | PXD043334 | Pride
Project description:4C-Seq has proven to be a powerful technique to identify genome-wide interactions with a single locus of interest (or "bait") that can be important for gene regulation. However, analysis of 4C-Seq data is complicated by the many biases inherent to the technique. An important consideration when dealing with 4C-Seq data is the differences in resolution of signal across the genome that result from differences in 3D distance separation from the bait. This leads to the highest signal in the region immediately surrounding the bait and increasingly lower signals in far-cis and trans. Another important aspect of 4C-Seq experiments is the resolution, which is greatly influenced by the choice of restriction enzyme and the frequency at which it can cut the genome. Thus, it is important that a 4C-Seq analysis method is flexible enough to analyze data generated using different enzymes and to identify interactions across the entire genome. Current methods for 4C-Seq analysis only identify interactions in regions near the bait or in regions located in far-cis and trans, but no method comprehensively analyzes 4C signals of different length scales. In addition, some methods also fail in experiments where chromatin fragments are generated using frequent cutter restriction enzymes. Here, we describe 4C-ker, a Hidden-Markov Model based pipeline that identifies regions throughout the genome that interact with the 4C bait locus. In addition, we incorporate methods for the identification of differential interactions in multiple 4C-seq datasets collected from different genotypes or experimental conditions. Adaptive window sizes are used to correct for differences in signal coverage in near-bait regions, far-cis and trans chromosomes. Using several datasets, we demonstrate that 4C-ker outperforms all existing 4C-Seq pipelines in its ability to reproducibly identify interaction domains at all genomic ranges with different resolution enzymes. 4C-Seq experiments from Igh and Cd83 bait in activated B cells and Tcrb (Eb) bait in double negative T cells and immature B cells. RNA-Seq and ATAC-Seq experiments in DN and Immature B cells.
2016-02-27 | E-GEOD-77645 | biostudies-arrayexpress
Project description:We screened for small molecules that reactivated latent HIV-1 and identified benzotriazoles as latency-reducing agents. Here, we characterize the effects of HODHBt on gene expression in cultured T cells from three donors by polyA RNA-Seq and on STAT5A occupancy of the HIV-1 LTR promoter by ChIP-Seq. These and other results demonstrate that benzotriazoles block SUMOylation of phosphorylated STAT5, prolonging its transcriptional activity.
2017-01-11 | GSE84199 | GEO
Project description:We screened for small molecules that reactivated latent HIV-1 and identified benzotriazoles as latency-reducing agents. Here, we characterize the effects of HODHBt on gene expression in cultured T cells from three donors by polyA RNA-Seq and on STAT5A occupancy of the HIV-1 LTR promoter by ChIP-Seq. These and other results demonstrate that benzotriazoles block SUMOylation of phosphorylated STAT5, prolonging its transcriptional activity.
2017-01-11 | GSE84197 | GEO