Project description:We have used RNA immunoprecipitation to identify the set of mRNAs that HIV-1 Tat interacts with in T-cells. We have also performed measurements of relative RNA abundance to determine if Tat binding is associated with an increase in RNA abundance in Tat-expressing T-cells and during HIV infection of primary T-cells. We have also used RNA IP and ChIP-Chip to compare the RNAs with which Tat interacts with to the RNAs that RISC interacts with and the genes associated with pTEF-b.
Project description:Integration of the HIV-1 provirus in the host genome ensures a persistent supply of latently infected cells. This latent reservoir is recalcitrant to antiretroviral therapy (ART) making lifelong treatment the only option for patients. The â??shock and killâ?? strategy aims to eradicate latent HIV by reactivating proviral gene expression followed by ART treatment. Gene specific transcriptional activation can be achieved using the RNA-guided CRISPR-Cas9 system comprising small guide RNAs (sgRNAs) with a nuclease deficient Cas9 mutant (dCas9) fused to the VP64 transactivation domain (dCas9-VP64).  We engineered this system to target 23 sites within the LTR promoter of HIV-1 and identified a â??hotspotâ?? for activation. We studied the functionality of activating sgRNAs to transcriptionally modulate the latent proviral genome across multiple different in vitro latency cell models including several J-Lat, ACH2 J1.1 and the CEM T cell model comprising a single clonal population of integrated mCherry-IRES-Tat from a full-length HIV LTR (LChIT). While we observed variable responses of latent cell models to well-characterized chemical stimuli, we detected consistent efficient activation of latent virus mediated by activator sgRNAs. In addition, transcriptome analysis of chemically treated cells revealed massive non-specific gene dysregulation whereas by comparison, dCas9-VP64/sgRNAs induced specific activation of the integrated provirus. In conclusion, we show the potential for CRISPR-mediated gene activation systems to provide enhanced efficiency and specificity in a targeted latency reactivation strategy. This represents a promising approach to a â??functional cureâ?? of HIV/AIDS. Three experimental conditions (sgRNA control, TNF treated and sgRNA against the LTR of HIV-1) were analyzed in triplicate using two sequencing lanes
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.
Project description:Schlafen-5 (SLFN5) is an interferon-induced protein of the Schlafen family which are involved in immune responses and oncogenesis. To date, little is known regarding its anti-HIV-1 function. Here, the authors report that overexpression of SLFN5 inhibits HIV-1 replication and reduces viral mRNA levels, whereas depletion of endogenous SLFN5 promotes HIV-1 replication. Moreover, they show that SLFN5 markedly decreases the transcriptional activity of HIV-1 long terminal repeat (LTR) via binding to two sequences in the U5-R region, which consequently represses the recruitment of RNA polymerase Ⅱ to the transcription initiation site. Mutagenesis studies show the importance of nuclear localization and the N-terminal 1-570 amino acids fragment in the inhibition of HIV-1. Further mechanistic studies demonstrate that SLFN5 interacts with components of the PRC2 complex, G9a and Histone H3, thereby promoting H3K27me2 and H3K27me3 modification leading to silencing HIV-1 transcription. In concert with this, they find that SLFN5 blocks the activation of latent HIV-1. Altogether, their findings demonstrate that SLFN5 is a transcriptional repressor of HIV-1 through epigenetic modulation and a potential determinant of HIV-1 latency.
Project description:HIV-1 Tat protein is essential for virus production. RNA-binding proteins that facilitate Tat production may be absent or downregulated in resting CD4+ T-cells, the main reservoir of latent HIV. In this study, we examined the role of Tat RNA-binding proteins on the expression of Tat and control of latent and productive infection.
Project description:The HIV-1 Trans-Activator of Transcription (Tat) protein binds to multiple host cellular factors and greatly enhances the level of transcription of the HIV genome. Here, we report the genome-wide binding map of Tat to the human genome in Jurkat T cells (Jurkat-Tat cells) using chromatin immunoprecipitation combined with next-generation sequencing. cDNA microarray was used to monitor gene expression changes between Jurkat and Jurkat-Tat cells. Additionally, we compared distribution of H3K9ac near gene promoters between Jurkat and Jurkat-Tat cells using ChIP-chip method and hybridized onto Agilent promoter array. Our data reveal that Tat’s interaction with the host genome is more extensive than previously thought, with potentially important implications for the viral life cycle. Agilent gene expression microarray was used to compare gene expression changes between Jurkat T cells and Jurkat T cells expressing HIV-Tat protein (Jurkat-Tat T cells) Expression profiles on Jurkat-Tat cells versus Jurkat cells. ChIP on chip for H3K9ac in Jurkat-Tat versus Jurkat cells. ChIP-seq for HIV-1 Tat protein in Jurkat-Tat cells.