Project description:We sought to explore the hypothesis that host factors required for HIV-1 replication also play a role in latency reversal. Using a CRISPR gene library of putative HIV dependency factors, we performed a screen to identify genes required for latency reactivation. We identified several HIV- 1 dependency factors that play a key role in HIV-1 latency reactivation including ELL, UBE2M, TBL1XR1, HDAC3, AMBRA1, and ALYREF. Knockout of Cyclin T1 (CCNT1), a component of the P-TEFb complex important for transcription elongation, was the top hit in the screen and had the largest effect on HIV latency reversal with a wide variety of latency reversal agents. Moreover, CCNT1 knockout prevents latency reactivation in a primary CD4+ T cell model of HIV latency without affecting activation of these cells. RNA sequencing data showed that CCNT1 regulates HIV-1 proviral genes to a larger extent than any other host gene and had no significant effects on RNA transcripts in primary T cells after activation. We conclude that CCNT1 function is redundant in T cells but is absolutely required for HIV latency reversal.
Project description:We sought to explore the hypothesis that host factors required for HIV-1 replication also play a role in latency reversal. Using a CRISPR gene library of putative HIV dependency factors, we performed a screen to identify genes required for latency reactivation. We identified several HIV- 1 dependency factors that play a key role in HIV-1 latency reactivation including ELL, UBE2M, TBL1XR1, HDAC3, AMBRA1, and ALYREF. Knockout of Cyclin T1 (CCNT1), a component of the P-TEFb complex important for transcription elongation, was the top hit in the screen and had the largest effect on HIV latency reversal with a wide variety of latency reversal agents. Moreover, CCNT1 knockout prevents latency reactivation in a primary CD4+ T cell model of HIV latency without affecting activation of these cells. RNA sequencing data showed that CCNT1 regulates HIV-1 proviral genes to a larger extent than any other host gene and had no significant effects on RNA transcripts in primary T cells after activation. We conclude that CCNT1 function is redundant in T cells but is absolutely required for HIV latency reversal.
Project description:The goal of this CRISPR-based screen (Latency HIV-CRISPR) is to identify HIV-1 latency factors by evaluating multiple pathways simultaneously. Here are Illumina sequencing data and counts files from a Latency HIV-CRISPR screen using a custom guide RNA library targeting human epigenome genes (HuEpi). The Latency HIV-CRISPR screens described here were performed in clonal ZAP knockout J-Lat 10.6 (PMID: 12682019) or J-Lat 5A8 (PMID: 24204950) cells lines as ZAP inhibition of the HIV-CRISPR vector has been previously described (PMID: 30520725). The screens were performed in the presence or absence of AZD5582, a SMAC mimetic and latency reversal agent, in order to identify factors that are dependent and independent of this transcriptional activator.
Project description:Latent HIV-1 infection represents a barrier to virus eradication as latent HIV-1 is impervious to the effects of antiretroviral drugs and can avoid detection by the host immune system. Strategies to clear latent HIV-1 infection in patients have so far failed in clinical trials to increase the decay rate of the latent reservoir underscoring the need for continued study of HIV-1 latency. In this study, a genome-wide RNAi screen was performed to probe cellular factors involved in maintaining HIV-1 latency in HeLa cells latently infected with an HIV-1 reporter virus.
Project description:Transcriptional silencing of latent HIV-1 proviruses entails complex and overlapping mechanisms and are a major barrier to in vivo elimination of HIV-1. We developed a new latency CRISPR screening strategy, called Latency HIV-CRISPR, which uses the packaging of guideRNA-encoding lentiviral vector genomes into the supernatant of budding virions as a direct readout of factors involved in the maintenance of HIV-1 latency. We developed a custom guideRNA library targeting epigenetic regulatory genes and paired the screen with and without a latency reversal agent – AZD5582, an activator of the non-canonical NFkB pathway – to examine a combination of mechanisms controlling HIV-1 latency. A component of the Nucleosome Acetyltransferase of H4 histone acetylation (NuA4 HAT) complex, ING3, acts in concert with AZD5582 to activate proviruses in J-Lat cell lines and in a primary CD4+ T cell model of HIV-1 latency. We found that the knockout of ING3 reduces acetylation of the H4 histone tail and BRD4 occupancy on the HIV-1 LTR, and the combination of ING3 knockout with the activation of non-canonical NFkB via AZD5582 act together to dramatically increase initiation and elongation of RNA Polymerase II on the HIV-1 provirus in a manner that is nearly unique among all cellular promoters.
Project description:To identify novel host factors as putative targets to reverse HIV-1 latency, we performed an insertional mutagenesis genetic screen in a latently HIV-1-infected pseudohaploid KBM7 cell line (Hap-Lat). Following mutagenesis, insertions were mapped to the genome, and bioinformatic analysis resulted in the identification of 69 candidate host genes involved in maintaining HIV-1 latency.
Project description:Purpose: The goal of this study is to identify host micro RNAs (miRNAs) whose expression is dysregulated during HIV latency, cell activation and productive infection. This information provides a mechanistic insight into an additional layer of miRNA-mediated regulation of gene expression and cellular pathways that are involved in HIV latency establishment and maintenance. Methods: An in vitro model of HIV latency and mock-infected cells before and after activation with antiCD3/antiCD28 coated magnetic beads was used for miRNA expression profiling using small RNA sequencing (smRNA-Seq). Results: Read counts of the 418 miRNAs survived filtering. Differential expression analysis identified 26 miRNAs dysregulated in latency. Messenger RNA (mRNA) targets and cellular pathways enriched for mRNA targets were identified using several analytical methods. Our analyses showed that many protein-coding genes and pathways targeted by dysregulated miRNAs have relevance to regulation of HIV expression or establishment of HIV latency. The p53 signalling pathway was found among pathways that were targeted by dysregulated miRNAs at a greater level than expected by chance. Conclusions: The present study identifies miRNAs dysregulated during HIV latency and provides a mechanistic insight into regulation of the p53 pathway via miRNAs that may contribute to latency establishment.
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.
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.