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: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: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:Thalidomide Exerts Distinct Molecular Antileukemic Effects and Combined Thalidomide/Fludarabine Therapy is Clinically Effective in High-Risk Chronic Lymphocytic Leukemia Background: Thalidomide represents a promising immunomodulatory drug that targets both leukemia cells and the tumor microenvironment. Methods: We treated chronic lymphocytic leukemia (CLL) patients with a combined thalidomide/fludarabine regimen and monitored cellular and molecular changes induced by thalidomide in-vivo prior to fludarabine treatment. Thalidomide was given daily (100mg p.o./day) and fludarabine was administered on days 7-11 (25 mg/m² i.v./day) within each 4-week cycle (maximum of 6 cycles). Twenty patients received thalidomide/fludarabine as first line therapy and 20 patients were previously treated. Unmutated IgVH mutation status was found in 36 cases and 13 had high-risk cytogenetic aberrations (deletion of 17p13 or 11q22-q23). Results: The overall response rate was 80% and 25% for untreated and previously treated patients, respectively. While thalidomide effectively reduced the number of CLL cells, the number of CD3 lymphocytes showed no significant change, but the number of CD4+CD25hiFOXP3+ T-regulatory cells was significantly decreased. Gene expression profiling revealed a thalidomide induced signature containing both targets known to play a role in immunomodulatory drug action as well as novel candidate genes. Conclusions: Combined thalidomide/fludarabine therapy demonstrated efficacy in high-risk CLL patients. Furthermore, our study provides novel biological insights into thalidomide effect, which might act by enhancing apoptosis of CLL cells and reducing Tregs, thereby enabling T-cell dependent anti-tumor effect.
Project description:Antiretroviral therapy (ART) has rendered HIV-1 infection a treatable illness; however, ART is not curative owing to the persistence of replication-competent, latent proviruses in long-lived resting T cells. Strategies that target these latently infected cells and allow immune recognition and clearance of this reservoir will be necessary to eradicate HIV-1 in infected individuals. This review describes current pharmacologic approaches to reactivate the latent reservoir so that infected cells can be recognized and targeted, with the ultimate goal of achieving an HIV-1 cure.
Project description:Alterations of IKZF1, encoding the lymphoid transcription factor IKAROS, are a hallmark of high risk acute lymphoblastic leukemia (ALL), however the role of IKZF1 alterations in ALL pathogenesis is poorly understood. Here we show that in mouse models of BCR-ABL1 leukemia, Ikzf1 and Arf alterations synergistically promote the development of an aggressive lymphoid leukemia. Ikzf1 alterations were associated with acquisition of stem cell-like features, including self-renewal and increased bone marrow stromal adhesion. Rexinoid receptor agonists reversed this phenotype, in part by inducing expression of IKZF1, resulting in abrogation of adhesion and self-renewal, cell cycle arrest and attenuation of proliferation without direct cytotoxicity. Retinoids potentiated the activity of dasatinib in mouse and human BCR-ABL1 ALL, providing a new therapeutic option in IKZF1-mutated ALL. Significance: The outcome of therapy for high-risk acute lymphoblastic leukemia remains suboptimal despite contemporary chemotherapy and the advent of targeted therapeutic approaches. Recent genomic studies have identified deletions or mutations of IKZF1 as a hallmark of high-risk ALL, but an understanding of how IKZF1 alteration contribute to leukemia development are lacking. Here we show that IKZF1 alterations drive lymphoid lineage, a stem cell-like phenotype, abnormal bone marrow adhesion, and poor responsiveness to tyrosine kinase inhibitor (TKI) therapy. Using a high-content screen, we show that retinoids reverse this phenotype in part by inducing expression of wild type IKZF1, and increase responsiveness to TKIs. These findings provide new insight into the pathogenesis of high-risk ALL and potential new therapeutic approaches. Pre-B mRNA profiles of p185 MIG and IK6 cells, DMSO or drug treated, in 3 or 4 replicates, using Illumina HiSeq 2500.
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:Analysis of the effect of Prednisolone in mouse splenocytes with and without Ikzf1 at gene expression level. The hypothesis tested in the present study was that loss of Ikzf1 affects the induction and repression of the Glucocorticoid receptor target genes. Results provide important information of the differentially expressed genes regulated by Ikzf1 upon Prednisolone treatment, explaining the resistance towards Glucocorticoid-induced apoptosis in splenocytes harboring Ikzf1 loss. Total RNA was obtained from WT and Ikzf1+/- splenocytes subjected to 16 hours Prednsiolone treatment compared to untreated cells.
Project description:To unravel the mechanisms of thalidomide developmental toxicity, we used microarrays to study transcriptomic changes induced by thalidomide during mouse embryonic stem cell (mESC) differentiation. C57BL/6 mESCs were allowed to differentiate spontaneously and global gene expression changes were studied using microarrays at at different time points after exposure to 0.25 mM thalidomide (THD).