A transient heritable memory regulates HIV reactivation from latency.
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ABSTRACT:
SUBMITTER: Lu Y
PROVIDER: S-EPMC8050369 | 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: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: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:Latency allows HIV-1 to persist in long-lived cellular reservoirs, preventing virus eradication. We have previously shown that the heat shock protein 90 (Hsp90) is required for HIV-1 gene expression and mediates greater HIV-1 replication in conditions of hyperthermia. Here we report that specific inhibitors of Hsp90 such as 17-(N-allylamino)-17-demethoxygeldanamycin and AUY922 prevent HIV-1 reactivation in CD4+ T cells. A single modification at position 19 in the Hsp90 inhibitors abolished this activity, supporting the specificity of the target. We tested the impact of Hsp90 on known pathways involved in HIV-1 reactivation from latency; they include protein kinase Cs(PKCs), mitogen activated protein kinase/extracellular signal regulated kinase/positive transcriptional elongation factor-b and NF-?B. We found that Hsp90 was required downstream of PKCs and was not required for mitogen activated protein kinase activation. Inhibition of Hsp90 reduced degradation of IkB? and blocked nuclear translocation of transcription factor p65/p50, suppressing the NF-?B pathway. Coimmunoprecipitation experiments showed that Hsp90 interacts with inhibitor of nuclear factor kappa-B kinase (IKK) together with cochaperone Cdc37, which is critical for the activity of several kinases. Targeting of Hsp90 by AUY922 dissociated Cdc37 from the complex. Therefore, Hsp90 controls HIV-1 reactivation from latency by keeping the IKK complex functional and thus connects T-cell activation with HIV-1 replication. AUY922 is in phase II clinical trial and, in combination with a PKC-? inhibitor in phase II clinical trial, almost completely suppressed HIV-1 reactivation at 15 nM with no cytotoxicity. Selective targeting of the Hsp90/Cdc37 interaction may provide a powerful approach to suppress HIV-1 reactivation from latency.
| S-EPMC3992654 | biostudies-literature
Project description:BackgroundCurrent antiretroviral therapy is effective in controlling HIV-1 infection. However, cessation of therapy is associated with rapid return of viremia from the viral reservoir. Eradicating the HIV-1 reservoir has proven difficult with the limited success of latency reactivation strategies and reflects the complexity of HIV-1 latency. Consequently, there is a growing need for alternate strategies. Here we explore a "block and lock" approach for enforcing latency to render the provirus unable to restart transcription despite exposure to reactivation stimuli. Reactivation of transcription from latent HIV-1 proviruses can be epigenetically blocked using promoter-targeted shRNAs to prevent productive infection. We aimed to determine if independent and combined expression of shRNAs, PromA and 143, induce a repressive epigenetic profile that is sufficiently stable to protect latently infected cells from HIV-1 reactivation when treated with a range of latency reversing agents (LRAs).ResultsJ-Lat 9.2 cells, a model of HIV-1 latency, expressing shRNAs PromA, 143, PromA/143 or controls were treated with LRAs to evaluate protection from HIV-1 reactivation as determined by levels of GFP expression. Cells expressing shRNA PromA, 143, or both, showed robust resistance to viral reactivation by: TNF, SAHA, SAHA/TNF, Bryostatin/TNF, DZNep, and Chaetocin. Given the physiological importance of TNF, HIV-1 reactivation was induced by TNF (5 ng/mL) and ChIP assays were performed to detect changes in expression of epigenetic markers within chromatin in both sorted GFP- and GFP+ cell populations, harboring latent or reactivated proviruses, respectively. Ordinary two-way ANOVA analysis used to identify interactions between shRNAs and chromatin marks associated with repressive or active chromatin in the integrated provirus revealed significant changes in the levels of H3K27me3, AGO1 and HDAC1 in the LTR, which correlated with the extent of reduced proviral reactivation. The cell line co-expressing shPromA and sh143 consistently showed the least reactivation and greatest enrichment of chromatin compaction indicators.ConclusionThe active maintenance of epigenetic silencing by shRNAs acting on the HIV-1 LTR impedes HIV-1 reactivation from latency. Our "block and lock" approach constitutes a novel way of enforcing HIV-1 "super latency" through a closed chromatin architecture that renders the virus resistant to a range of latency reversing agents.
| S-EPMC6172763 | biostudies-literature
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 Keywords: time-course
2004-08-16 | GSE1441 | GEO
Project description:UnlabelledAntiretroviral therapy (ART) inhibits HIV-1 replication, but the virus persists in latently infected resting memory CD4(+) T cells susceptible to viral reactivation. The virus-encoded early gene product Tat activates transcription of the viral genome and promotes exponential viral production. Here we show that the Tat inhibitor didehydro-cortistatin A (dCA), unlike other antiretrovirals, reduces residual levels of viral transcription in several models of HIV latency, breaks the Tat-mediated transcriptional feedback loop, and establishes a nearly permanent state of latency, which greatly diminishes the capacity for virus reactivation. Importantly, treatment with dCA induces inactivation of viral transcription even after its removal, suggesting that the HIV promoter is epigenetically repressed. Critically, dCA inhibits viral reactivation upon CD3/CD28 or prostratin stimulation of latently infected CD4(+) T cells from HIV-infected subjects receiving suppressive ART. Our results suggest that inclusion of a Tat inhibitor in current ART regimens may contribute to a functional HIV-1 cure by reducing low-level viremia and preventing viral reactivation from latent reservoirs.ImportanceAntiretroviral therapy (ART) reduces HIV-1 replication to very low levels, but the virus persists in latently infected memory CD4(+) T cells, representing a long-lasting source of resurgent virus upon ART interruption. Based on the mode of action of didehydro-cortistatin A (dCA), a Tat-dependent transcription inhibitor, our work highlights an alternative approach to current HIV-1 eradication strategies to decrease the latent reservoir. In our model, dCA blocks the Tat feedback loop initiated after low-level basal reactivation, blocking transcriptional elongation and hence viral production from latently infected cells. Therefore, dCA combined with ART would be aimed at delaying or halting ongoing viral replication, reactivation, and replenishment of the latent viral reservoir. Thus, the latent pool of cells in an infected individual would be stabilized, and death of the long-lived infected memory T cells would result in a continuous decay of this pool over time, possibly culminating in the long-awaited sterilizing cure.
| S-EPMC4495168 | biostudies-literature
Project description:Latent HIV-1 provirus represents the barrier toward a cure for infection and is dependent upon the host RNA Polymerase (Pol) II machinery for reemergence. Here, we find that inhibitors of the RNA Pol II mediator kinases CDK8/19, Senexin A and BRD6989, inhibit induction of HIV-1 expression in response to latency-reversing agents and T cell signaling agonists. These inhibitors were found to impair recruitment of RNA Pol II to the HIV-1 LTR. Furthermore, HIV-1 expression in response to several latency reversal agents was impaired upon disruption of CDK8 by shRNA or gene knockout. However, the effects of CDK8 depletion did not entirely mimic CDK8/19 kinase inhibition suggesting that the mediator kinases are not functionally redundant. Additionally, treatment of CD4+ peripheral blood mononuclear cells isolated from people living with HIV-1 and who are receiving antiretroviral therapy with Senexin A inhibited induction of viral replication in response to T cell stimulation by PMA and ionomycin. These observations indicate that the mediator kinases, CDK8 and CDK19, play a significant role for regulation of HIV-1 transcription and that small molecule inhibitors of these enzymes may contribute to therapies designed to promote deep latency involving the durable suppression of provirus expression. IMPORTANCE A cure for HIV-1 infection will require novel therapies that can force elimination of cells that contain copies of the virus genome inserted into the cell chromosome, but which is shut off, or silenced. These are known as latently-infected cells, which represent the main reason why current treatment for HIV/AIDS cannot cure the infection because the virus in these cells is unaffected by current drugs. Our results indicate that chemical inhibitors of Cdk8 also inhibit the expression of latent HIV provirus. Cdk8 is an important enzyme that regulates the expression of genes in response to signals to which cells need to respond and which is produced by a gene that is frequently mutated in cancers. Our observations indicate that Cdk8 inhibitors may be employed in novel therapies to prevent expression from latent provirus, which might eventually enable infected individuals to cease treatment with antiretroviral drugs.
| S-EPMC10537590 | biostudies-literature
Project description:Cells harboring latent HIV-1 pose a major obstacle to eradication of the virus. The 'shock and kill' strategy has been broadly explored to purge the latent reservoir; however, none of the current latency-reversing agents (LRAs) can safely and effectively activate the latent virus in patients. In this study, we report an ingenol derivative called EK-16A, isolated from the traditional Chinese medicinal herb Euphorbia kansui, which displays great potential in reactivating latent HIV-1. A comparison of the doses used to measure the potency indicated EK-16A to be 200-fold more potent than prostratin in reactivating HIV-1 from latently infected cell lines. EK-16A also outperformed prostratin in ex vivo studies on cells from HIV-1-infected individuals, while maintaining minimal cytotoxicity effects on cell viability and T cell activation. Furthermore, EK-16A exhibited synergy with other LRAs in reactivating latent HIV-1. Mechanistic studies indicated EK-16A to be a PKCγ activator, which promoted both HIV-1 transcription initiation by NF-κB and elongation by P-TEFb signal pathways. Further investigations aimed to add this compound to the therapeutic arsenal for HIV-1 eradication are in the pipeline.
| S-EPMC5573388 | biostudies-literature