Distinct chromatin functional states correlate with HIV latency reactivation in infected primary CD4+ T cells.
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ABSTRACT:
SUBMITTER: Battivelli E
PROVIDER: S-EPMC5973828 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The use of antiretroviral therapy in HIV type 1 (HIV-1)-infected patients does not lead to virus eradication. This is due, to a significant degree, to the fact that HIV-1 can establish a highly stable reservoir of latently infected cells. In this work, we describe an ex vivo experimental system that generates high levels of HIV-1 latently infected memory cells using primary CD4+ T cells. Using this model, we were able to dissect the T cell-signaling pathways and to characterize the long terminal repeat (LTR) cis-acting elements involved in reactivation of HIV-1 in memory CD4+ T cells. We conclude that Lck and nuclear factor of activated T cells (NFAT), but not NF-kappaB, are required for optimal latent virus reactivation in memory T cells. We also found that the cis-acting elements which are critical toward HIV-1 reactivation are the Sp1 and kappaB/NFAT transcription factor binding sites.
| S-EPMC2614643 | biostudies-literature
Project description:HIV latency is a major obstacle to curing infection. Current strategies to eradicate HIV aim at increasing transcription of the latent provirus. In the present study we observed that latently infected CD4+ T cells from HIV-infected individuals failed to produce viral particles upon ex vivo exposure to SAHA (vorinostat), despite effective inhibition of histone deacetylases. To identify steps that were not susceptible to the action of SAHA or other latency reverting agents, we used a primary CD4+ T cell model, joint host and viral RNA sequencing, and a viral-encoded reporter. This model served to investigate the characteristics of latently infected cells, the dynamics of HIV latency, and the process of reactivation induced by various stimuli. During latency, we observed persistence of viral transcripts but only limited viral translation. Similarly, the reactivating agents SAHA and disulfiram successfully increased viral transcription, but failed to effectively enhance viral translation, mirroring the ex vivo data. This study highlights the importance of post-transcriptional blocks as one mechanism leading to HIV latency that needs to be relieved in order to purge the viral reservoir.
| S-EPMC4038609 | biostudies-literature
Project description:HIV latency is a major obstacle to curing infection. Current strategies to eradicate HIV aim at increasing transcription of the latent provirus. In the present study we observed that latently infected CD4+ T cells from HIV-infected individuals failed to produce viral particles upon ex vivo exposure to SAHA (vorinostat), despite effective inhibition of histone deacetylases. To identify steps that were not susceptible to the action of SAHA or other latency reverting agents, we used a primary CD4+ T cell model, joint host and viral RNA sequencing, and a viral-encoded reporter. This model served to investigate the characteristics of latently infected cells, the dynamics of HIV latency, and the process of reactivation induced by various stimuli. During latency, we observed persistence of viral transcripts but only limited viral translation. Similarly, the reactivating agents SAHA and disulfiram successfully increased viral transcription, but failed to effectively enhance viral translation, mirroring the ex vivo data. This study highlights the importance of post-transcriptional blocks as one mechanism leading to HIV latency that needs to be relieved in order to purge the viral reservoir.
2017-02-24 | GSE95297 | GEO
Project description:The latent HIV-1 reservoir of memory CD4+ T cells that persists during combination antiviral therapy prevents a cure of infection. Insight into mechanisms of latency and viral reactivation are essential for the rational design of strategies to reduce the latent reservoir. In this study, we quantified the levels of >2,600 proteins in the CCL19 primary CD4+ T cell model of HIV-1 latency. We profiled proteins under conditions that promote latent infection and after cells were treated with phorbol 12-myristate 13-acetate (PMA) + ionomycin, which is known to efficiently induce reactivation of latent HIV-1. In an analysis of cells from two healthy blood donors, we identified 61 proteins that were upregulated ?2-fold, and 36 proteins that were downregulated ?2-fold under conditions in which latent viruses were reactivated. These differentially expressed proteins are, therefore, candidates for cellular factors that regulate latency or viral reactivation. Two unexpected findings were obtained from the proteomic data: (1) the interactions among the majority of upregulated proteins are largely undetermined in published protein-protein interaction networks and (2) downregulated proteins are strongly associated with Gene Ontology terms related to mitochondrial protein synthesis. This proteomic data set provides a useful resource for future mechanistic studies of HIV-1 latency.
| S-EPMC5771535 | biostudies-literature
Project description:DNA methylation of retroviral promoters and enhancers localized in the provirus 5' long terminal repeat (LTR) is considered to be a mechanism of transcriptional suppression that allows retroviruses to evade host immune responses and antiretroviral drugs. However, the role of DNA methylation in the control of HIV-1 latency has never been unambiguously demonstrated, in contrast to the apparent importance of transcriptional interference and chromatin structure, and has never been studied in HIV-1-infected patients. Here, we show in an in vitro model of reactivable latency and in a latent reservoir of HIV-1-infected patients that CpG methylation of the HIV-1 5' LTR is an additional epigenetic restriction mechanism, which controls resistance of latent HIV-1 to reactivation signals and thus determines the stability of the HIV-1 latency. CpG methylation acts as a late event during establishment of HIV-1 latency and is not required for the initial provirus silencing. Indeed, the latent reservoir of some aviremic patients contained high proportions of the non-methylated 5' LTR. The latency controlled solely by transcriptional interference and by chromatin-dependent mechanisms in the absence of significant promoter DNA methylation tends to be leaky and easily reactivable. In the latent reservoir of HIV-1-infected individuals without detectable plasma viremia, we found HIV-1 promoters and enhancers to be hypermethylated and resistant to reactivation, as opposed to the hypomethylated 5' LTR in viremic patients. However, even dense methylation of the HIV-1 5'LTR did not confer complete resistance to reactivation of latent HIV-1 with some histone deacetylase inhibitors, protein kinase C agonists, TNF-alpha, and their combinations with 5-aza-2deoxycytidine: the densely methylated HIV-1 promoter was most efficiently reactivated in virtual absence of T cell activation by suberoylanilide hydroxamic acid. Tight but incomplete control of HIV-1 latency by CpG methylation might have important implications for strategies aimed at eradicating HIV-1 infection.
| S-EPMC2722084 | biostudies-literature
Project description:Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiologic agent of three human malignancies, the endothelial cell cancer Kaposi's sarcoma, and two B cell cancers, Primary Effusion Lymphoma and multicentric Castleman's disease. KSHV has latent and lytic phases of the viral life cycle, and while both contribute to viral pathogenesis, lytic proteins contribute to KSHV-mediated oncogenesis. Reactivation from latency is driven by the KSHV lytic gene transactivator RTA, and RTA transcription is controlled by epigenetic modifications. To identify host chromatin-modifying proteins that are involved in the latent to lytic transition, we screened a panel of inhibitors that target epigenetic regulatory proteins for their ability to stimulate KSHV reactivation. We found several novel regulators of viral reactivation: an inhibitor of Bmi1, PTC-209, two additional histone deacetylase inhibitors, Romidepsin and Panobinostat, and the bromodomain inhibitor (+)-JQ1. All of these compounds stimulate lytic gene expression, viral genome replication, and release of infectious virions. Treatment with Romidepsin, Panobinostat, and PTC-209 induces histone modifications at the RTA promoter, and results in nucleosome depletion at this locus. Finally, silencing Bmi1 induces KSHV reactivation, indicating that Bmi1, a member of the Polycomb repressive complex 1, is critical for maintaining KSHV latency.
| S-EPMC6136816 | biostudies-other
Project description:Cells: ACH-2, and A3.01, were obtained through the NIH AIDS Research and Reference Reagent Program, Division of AIDS, NIAID, NIH. ACH-2, is a chronically infected cell line harboring HIV-1 LAV strain, while A3.01 is the corresponding parental uninfected cell line. Cells were grown in RPMI-1640 (Invitrogen, San Diego, CA) with 10% fetal bovine serum (FBS, Invitrogen), 5% penicillin-streptomycin (Invitrogen), and 2mM glutamine (Invitrogen). Cells were maintained at a concentration of 1x10e6 cells/ml in T-175 flasks. Cell concentrations and cell viability were monitored throughout the experiment at all time points studied. Cells were induced by addition of 20 ng/mL of phorbol myristyl acetate (PMA or TPA, Sigma, St Louis, MO) for one hour, after which the cells were washed with phosphate buffered saline (PBS). Cells were harvested by centrifugation at 1000 rpm for 10 minutes, at the following times after induction, 0.5, 3, 6, 8, 12, 18, 24, 48, 72, and 96 hour(s). HIV-infected and uninfected cells maintained and harvested in parallel with the PMA-treated cells, but not induced with PMA ( No PMA)were also harvested. Harvested cells were washed thrice with ice-cold PBS to remove media; cell pellets were snap frozen using ethanol-dry ice mixture and stored at (80°C for subsequent RNA extraction. Total RNA Extraction: Total RNA was extracted using RNEasy Midiprep Kits per manufacturer's protocol (Qiagen, Valencia, CA). RNA concentrations and purity were measured by spectrophotometry, RNA quality (absence of RNA degradation) was assessed by gel electrophoresis. RNA concentration was adjusted to the levels required for subsequent microarray experiment protocols by concentration in a SpeedVac (Savant Instruments, Holbrook, CA). RNA samples (6-7 µg/µL) were stored in 100 µL TE buffer at -80°C. Microarray Studies: Total RNA obtained from induced chronically infected and corresponding uninfected parental cells were used for microarray experiments. For each time point, RNA from the induced chronically infected ACH-2 cells and RNA from the corresponding induced, uninfected A3.01 cells were compared to minimize effects due to PMA induction. Microarrays were obtained from the National Cancer Institute Microarray Facility, Advanced Technology Center (Gaithersburg, MD). The microarrays (Hs. UniGem2) contained 10,368 cDNA spots on each glass slide. The cDNAs were selected for spotting on the slides based on their known or probable involvement in oncogenesis, signal transduction, apoptosis, immune function, inflammatory pathways, cellular transport, transcription, protein translation and other important cellular functions. A number of expressed sequence tags (ESTs) from unknown genes homologous to known genes and cDNAs encoding housekeeping genes were also included in these gene sets. For each time point, 50 µg of total RNA from PMA induced ACH-2 cells and 70 µg of total RNA from PMA induced A3.01 cells was labeled with Cy-3-dUTP and Cy-5-dUTP respectively. Higher amounts of RNA were used for Cy-5 labeling to minimize the disparities in dye incorporation. Each sample of RNA from PMA-induced, infected cells from a particular time point was compared with RNA from the corresponding PMA-induced, uninfected cells from the same time point for subsequent hybridization to the same array to ensure accurate comparisons and to eliminate inter-array variability. Following reverse transcription, the labeled cDNAs were then combined and purified using MicroCon YM-30 (Millipore, Bedford, MA) spin column filters, to remove any unincorporated nucleotides. 8-10 µg each of Cot-1 DNA, (Boehringer Mannheim, Indianapolis, IN), yeast tRNA (Sigma) and polyA (Amersham Biosciences) were added to the reaction mixture and heated at 100°C for 1 minute. Hybridization of the labeled cDNA to the microarray was carried out at 65°C overnight, followed by washes with 1X SSC, 0.2X SSC and 0.05X SSC respectively. The slides were dried by centrifugation at 1000 rpm for 3 minutes and then scanned as described below. Microarray Scanning and Data Analysis: The slides were scanned using an Axon GenePix 4000 scanner (Axon Instruments, Union City, CA). The photomultiplier tube values (PMT) were adjusted to obtain equivalent intensities at both wavelengths used, 635 nm and 532 nm for the Cy5 and Cy3 channels respectively. Image analysis was performed using GenePix analysis software (Axon Instruments) and data analysis was performed using the microArray Database (mAdb) system hosted by the Center for Information Technology and Center for Cancer Research at NIH (http://nciarray.nci.nih.gov/). Keywords = HIV Keywords = latency
2010-06-06 | E-GEOD-1441 | biostudies-arrayexpress
Project description:The eradication of HIV-1 will likely require novel clinical approaches to purge the reservoir of latently infected cells from a patient. We hypothesize that this therapy should target a wide range of latent integration sites, act effectively against viral variants that have acquired mutations in their promoter regions, and function across multiple HIV-1 subtypes. By using primary CD4(+) and Jurkat cell-based in vitro HIV-1 latency models, we observe that single-agent latency reactivation therapy is ineffective against most HIV-1 subtypes. However, we demonstrate that the combination of two clinically promising drugs-namely, prostratin and suberoylanilide hydroxamic acid (SAHA)-overcomes the limitations of single-agent approaches and can act synergistically for many HIV-1 subtypes, including A, B, C, D, and F. Finally, by identifying the proviral integration position of latent Jurkat cell clones, we demonstrate that this drug combination does not significantly enhance the expression of endogenous genes nearest to the proviral integration site, indicating that its effects may be selective.
| S-EPMC2876650 | biostudies-literature
Project description:Reactivation of human immunodeficiency virus 1 (HIV-1) from latently infected T cells is a critical barrier to cure patients. It remains unknown whether reactivation of individual latent cells occurs stochastically in response to latency reversal agents (LRAs) or is a deterministic outcome of an underlying cell state. To characterize these single-cell responses, we leverage the classical Luria-Delbrück fluctuation test where single cells are isolated from a clonal population and exposed to LRAs after colony expansion. Data show considerable colony-to-colony fluctuations with the fraction of reactivating cells following a skewed distribution. Modeling systematic measurements of fluctuations over time uncovers a transient heritable memory that regulates HIV-1 reactivation, where single cells are in an LRA-responsive state for a few weeks before switching back to an irresponsive state. These results have enormous implications for designing therapies to purge the latent reservoir and further utilize fluctuation-based assays to uncover hidden transient cellular states underlying phenotypic heterogeneity.
| S-EPMC8050369 | biostudies-literature
Project description:Despite the effectiveness of highly active antiretroviral therapy (HAART) in treating individuals infected with HIV, HAART is not a cure. A latent reservoir, composed mainly of resting CD4+T cells, drives viral rebound once therapy is stopped. Understanding the formation and maintenance of latently infected cells could provide clues to eradicating this reservoir. However, there have been discrepancies regarding the susceptibility of resting cells to HIV infection in vitro and in vivo. As we have previously shown that resting CD4+T cells are susceptible to HIV integration, we asked whether these cells were capable of producing viral proteins and if so, why resting cells were incapable of supporting productive infection. To answer this question, we spinoculated resting CD4+T cells with or without prior stimulation, and measured integration, transcription, and translation of viral proteins. We found that resting cells were capable of producing HIV Gag without supporting spreading infection. This block corresponded with low HIV envelope levels both at the level of protein and RNA and was not an artifact of spinoculation. The defect was reversed upon stimulation with IL-7 or CD3/28 beads. Thus, a population of latent cells can produce viral proteins without resulting in spreading infection. These results have implications for therapies targeting the latent reservoir and suggest that some latent cells could be cleared by a robust immune response.
| S-EPMC3406090 | biostudies-literature