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.
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: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. We demonstrate that, by targeting IKZF1 for degradation, these compounds reverse HIV-1 latency in CD4+ T-cells isolated from virally suppressed people living with HIV-1 and that they are able to synergize with other known LRAs.
Project description:The goal of this study was to utilize CaptureSeq to be able to measure HIV-1 transcription after reversal of latency in primary cells from antiretroviral-treated HIV-1 infected individuals.
Project description:T cells are the primary target of the virus HIV-1. Upon infection, the expression of the virus may come to a complete shutdown, a phenomenon known as latency. The molecular mechanisms responsible for the latency of HIV-1 are still poorly understood. To shed light on those mechanisms, we used the J-Lat A2 model for latency reversal, that consists of a Jurkat T cell clone containing a mini HIV construct that is transcriptionally silent. We treated J-Lat A2 and Jurkat cells with the latency-reversing drugs SAHA (suberoylanilide hydroxamic acid) and PMA (phorbol 12-myristate 13-acetate), and we performed single-cell RNA-seq to identify transcriptional signatures shared among the cells where HIV is reactivated.
Project description:Molecules mimicking the active N-terminal tetrapeptide of the second mitochondrial-derived activator of caspases (SMACm) potently reverse HIV latency in vitro and ex vivo without the pleotropic cellular effects seen with other LRAs. We verified that SMACm facilitate latency reversal through activation of the non-canonical NFκB pathway as exemplified by rapid degradation of cIAP1, followed by a slower conversion of inactive p100 into active p52. A potent representative of this class, AZD5582, increases cell-associated HIV gag RNA expression in resting CD4+ T cells from ART-suppressed, HIV-infected donors while altering the expression of a restricted number of human genes. These findings represent the first demonstration that SMACm have single agent latency reversal activity in patient-derived cells and support evaluation of SMACm in preclinical animal models.
Project description:Latency reversal and clearance strategies for HIV cure are beginning to employ IAP antagonists (IAPi) to induce unprecedented levels of latent reservoir expression without immunotoxicity during suppressive antiretroviral therapy (ART). However, full targeting of the reservoir may require combinatorial approaches. A Jurkat latency model screen for IAPi combination partners demonstrated synergistic latency reversal with Bromodomain and Extra-Terminal domain protein inhibitors (BETi). Mechanistic investigations using CRISPR-CAS9 and single cell-RNAseq informed comprehensive ex vivo evaluations of IAPi plus pan-BET, bromodomain (BD)-selective BET, or selective BET isoform targeting in CD4 T cells from ART-suppressed donors. IAPi+BETi treatment resulted in striking induction of cell-associated HIV gag RNA but lesser induction of fully elongated and tat-rev RNA, especially compared to T cell activation positive controls. IAPi/BETi resulted in HIV protein induction in bulk cultures of CD4 T cells using an ultrasensitive p24 assay, but did not translate to enhanced viral outgrowth frequency using a standard quantitative viral outgrowth assay. Overall, this study defines HIV transcriptional elongation and splicing as key barriers to latent HIV protein expression following latency reversal, delineates the roles of BET proteins and their bromodomains in HIV latency, and provides rationale for testing of IAPi+BETi in animal models of HIV latency.
Project description:Multiple myeloma is a plasma cell malignancy that is susceptible to drugs targeting protein homeostasis such as thalidomide analogues and proteasome inhibitors. Thalidomide analogues modulate the activity of DDB1/CUL4 E3-ligase complexes to perturb substrate recognition and proteasomal degradation thereof. We hypothesised that the cellular pool of DDB1/CUL4 associated factors (DCAFs) may mediate other essential plasma cell processes and offer new targets for therapeutic intervention. Utilising B32B3, a previously disclosed DCAF1 kinase inhibitor as a template, we developed a series of analogues with enhanced anti-myeloma potency.
Project description:The barrier to HIV-1 functional cure is caused by a small pool of latently infected resting CD4 T-cells that persist under antiretroviral therapy. Notably this latent reservoir of infected cells will produce replication-competent infectious virus once prolonged suppressive HAART is withdrawn. The reactivation of HIV-1 gene expression in T-cells harboring latent provirus in HIV-1 patients under HAART will likely result in depletion of this latent reservoir due to cytopathic effects and immune clearance. Many studies have investigated small molecules that reactivate HIV-1 gene expression but to date no latency reversal agent (LRA) has been identified to be specific, non-toxic, and effective in primary T-cells isolated from HIV-1 infected individuals undergoing long-term HAART. Stochastic fluctuations in HIV-1 tat gene expression have been attributed to be essential in the viral progression to latency. We hypothesized that exposing Tat to latently infected CD4 T-cells will result in potent latency reversal. Our results indicate the capacity of an engineered Tat to reactivate HIV-1 in latently infected cells from patients to a similar degree as the protein kinase C agonist PMA (Phorbol 12-Myristate 13-Acetate) while showing no T-cell activation nor any significant transcriptome perturbation in primary CD4 T-cells.
Project description:Multiple myeloma is a plasma cell malignancy that is susceptible to drugs targeting protein homeostasis such as thalidomide analogues and proteasome inhibitors. Thalidomide analogues modulate the activity of DDB1/CUL4 E3-ligase complexes to perturb substrate recognition and proteasomal degradation thereof. We hypothesised that the cellular pool of DDB1/CUL4 associated factors (DCAFs) may mediate other essential plasma cell processes and offer new targets for therapeutic intervention. Unbiased genetic screening identified DCAF1 (also known as Vpr-binding protein; VPRBP) as essential for myeloma cell survival with a multidomain structure offering several distinct opportunities for drug development. Utilising B32B3, a previously disclosed DCAF1 kinase inhibitor as a template, we developed a series of analogues with enhanced anti-myeloma potency. As anti-myeloma activity did not associate with dephosphorylation of known DCAF1 kinase substrates, we correlated drug-induced cellular phenotypes with whole-genome CRISPR/Cas9 resistance screening to further define mechanistic activity. These studies identified B32B3 analogues as microtubular destabilising agents with potential DCAF1 kinase independent properties and in vivo efficacy in multiple myeloma and lymphoma.