scholarly journals HMBA Enhances Prostratin-Induced Activation of Latent HIV-1 via Suppressing the Expression of Negative Feedback Regulator A20/TNFAIP3 in NF-κB Signaling

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Duchu Chen ◽  
Huiping Wang ◽  
Jude Juventus Aweya ◽  
Yanheng Chen ◽  
Meihua Chen ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Negative Feedback ◽  
Transcriptional Activation ◽  
Transcription Initiation ◽  
Nuclear Translocation ◽  
Cellular Target ◽  
Negative Feedback Circuit ◽  
Latent Hiv ◽  
Hiv 1 ◽  
Feedback Regulator

In the past decade, much emphasis has been put on the transcriptional activation of HIV-1, which is proposed as a promised strategy for eradicating latent HIV-1 provirus. Two drugs, prostratin and hexamethylene bisacetamide (HMBA), have shown potent effects as inducers for releasing HIV-1 latency when used alone or in combination, although their cellular target(s) are currently not well understood, especially under drug combination. Here, we have shown that HMBA and prostratin synergistically release HIV-1 latency via different mechanisms. While prostratin strongly stimulates HMBA-induced HIV-1 transcription via improved P-TEFb activation, HMBA is capable of boosting NF-κB-dependent transcription initiation by suppressing prostratin-induced expression of the deubiquitinase A20, a negative feedback regulator in the NF-κB signaling pathway. In addition, HMBA was able to increase prostratin-induced phosphorylation and degradation of NF-κB inhibitor IκBα, thereby enhancing and prolonging prostratin-induced nuclear translocation of NF-κB, a prerequisite for stimulation of transcription initiation. Thus, by blocking the negative feedback circuit, HMBA functions as a signaling enhancer of the NF-κB signaling pathway.

scholarly journals Transcriptional Activation of the Integrated Chromatin-Associated Human Immunodeficiency Virus Type 1 Promoter

1998 ◽  
Vol 18 (5) ◽  
pp. 2535-2544 ◽  
Author(s):  
Aboubaker El Kharroubi ◽  
Graziella Piras ◽  
Ralf Zensen ◽  
Malcolm A. Martin
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Chromatin Structure ◽  
Transcriptional Activation ◽  
Transcription Initiation ◽  
Core Promoter ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The regulation of human immunodeficiency virus type 1 (HIV-1) gene expression involves a complex interplay between cellular transcription factors, chromatin-associated proviral DNA, and the virus-encoded transactivator protein, Tat. Here we show that Tat transactivates the integrated HIV-1 long terminal repeat (LTR), even in the absence of detectable basal promoter activity, and this transcriptional activation is accompanied by chromatin remodeling downstream of the transcription initiation site, as monitored by increased accessibility to restriction endonucleases. However, with an integrated promoter lacking both Sp1 and NF-κB sites, Tat was unable to either activate transcription or induce changes in chromatin structure even when it was tethered to the HIV-1 core promoter upstream of the TATA box. Tat responsiveness was observed only when Sp1 or NF-κB was bound to the promoter, implying that Tat functions subsequent to the formation of a specific transcription initiation complex. Unlike Tat, NF-κB failed to stimulate the integrated transcriptionally silent HIV-1 promoter. Histone acetylation renders the inactive HIV-1 LTR responsive to NF-κB, indicating that a suppressive chromatin structure must be remodeled prior to transcriptional activation by NF-κB. Taken together, these results suggest that Sp1 and NF-κB are required for the assembly of transcriptional complexes on the integrated viral promoter exhibiting a continuum of basal activities, all of which are fully responsive to Tat.

scholarly journals Physical and functional interaction between the ID1 and p65 for activation of NF-κB

2012 ◽  
Vol 303 (3) ◽  
pp. C267-C277 ◽  
Author(s):  
Xiao Peng ◽  
Yuna Wang ◽  
Swapna Kolli ◽  
Junpeng Deng ◽  
Li Li ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Transcriptional Activation ◽  
Nuclear Translocation ◽  
Luciferase Assay ◽  
Physical Interaction ◽  
Site Mutation ◽  
Transcriptional Activation Domain ◽  
Apoptosis Protein

Inhibitor of differentiation or DNA binding-1 (ID1) is an important helix-loop-helix (HLH) transcription factor involved in diverse biological functions including cell differentiation, proliferation, apoptosis, and senescence. Recently, it was reported that ID1 can activate the NF-κB signaling pathway in a variety of cancer cells and a T cell line, but the mechanisms involved in ID1-mediated transactivation of NF-κB are not clear. In this study, we demonstrate by both in vitro pull-down assays and a cell-based in vivo two-hybrid system that ID1-mediated NF-κB activation is due to its physical interaction with p65. We have identified that the transcriptional activation domain (TAD) in p65 and the HLH domain in ID1 are vital for their interaction. Interestingly, a single site mutation (Leu76) in the HLH domain of ID1 protein drastically decreased its ability to bind with p65. Using a dual-luciferase assay, we demonstrated that the interaction between ID1 and p65 modulates activation of the NF-κB signaling pathway in vivo. In addition, we demonstrated that, by affecting the nuclear translocation of p65, ID1 is essential in regulating TNF-α-induced p65 recruitment to its downstream target, the cellular inhibitor of apoptosis protein 2 (cIAP2) promoter.

scholarly journals Multisite phosphorylation by Cdk1 initiates delayed negative feedback to control mitotic transcription

2021 ◽  
Author(s):  
Jonathan B. Asfaha ◽  
Mihkel Örd ◽  
Mart Loog ◽  
David O. Morgan
Keyword(s):  
Gene Expression ◽  
Negative Feedback ◽  
Transcriptional Activation ◽  
Mitotic Arrest ◽  
Cyclin Dependent Kinase ◽  
Feedback Circuit ◽  
Mitotic Progression ◽  
Transcriptional Program ◽  
Multisite Phosphorylation ◽  
Negative Feedback Circuit

AbstractOrdered phosphorylation of cyclin-dependent kinase (CDK) substrates leads to the sequential transcriptional activation and inhibition of hundreds of cell cycle-regulated genes. We find that Ndd1, an activator of genes required for mitotic progression, is both positively and negatively regulated by CDK activity. CDK activity initially stimulates Ndd1-dependent transcription as cells enter mitosis, but prolonged high CDK activity in a mitotic arrest inhibits transcription. The result is a time-delayed negative feedback circuit that generates a pulse of mitotic gene expression. Our results suggest that high CDK activity catalyzes the formation of multiple weak phosphodegrons on Ndd1, leading to its destabilization. Cyclin specificity and phosphorylation kinetics contribute to the timing of Ndd1 destruction. Failure to degrade Ndd1 in a mitotic arrest leads to elevated mitotic gene expression. We conclude that a combination of positive and negative Ndd1 regulation by CDKs governs the timing and magnitude of the mitotic transcriptional program.

scholarly journals Cyclophilin A is a key positive and negative feedback regulator within interleukin‐6 trans‐signaling pathway

2021 ◽  
Vol 35 (11) ◽  
Author(s):  
Xiaohan Luan ◽  
Wenxian Yang ◽  
Xiaoyuan Bai ◽  
Heqiao Li ◽  
Huizi Li ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Negative Feedback ◽  
Interleukin 6 ◽  
Cyclophilin A ◽  
Positive And Negative Feedback ◽  
Feedback Regulator

scholarly journals Inhibition of Polo-like kinase 1 (PLK1) facilitates the elimination of HIV-1 viral reservoirs in CD4+ T cells ex vivo

2020 ◽  
Vol 6 (29) ◽  
pp. eaba1941
Author(s):  
Dawei Zhou ◽  
Tsuyoshi Hayashi ◽  
Maxime Jean ◽  
Weili Kong ◽  
Guillaume Fiches ◽  
...  
Keyword(s):  
T Cells ◽  
Nuclear Translocation ◽  
De Novo ◽  
Ex Vivo ◽  
Critical Role ◽  
Protein Stabilization ◽  
Viral Reservoirs ◽  
Promising Target ◽  
Latent Hiv ◽  
Hiv 1

Although combination antiretroviral therapy is effective in controlling HIV-1 infection, latent HIV-1 proviruses cannot be eliminated. HIV-1 reactivation induced by the mere use of latency-reversing agents is insufficient to render death of reservoir cells, indicating that certain intrinsic survival mechanisms exist. We report that Polo-like kinase 1 (PLK1) plays a critical role in survival of CD4+ T cells that undergo HIV-1 reactivation from latency or de novo infection. PLK1 is elevated in both scenarios, which requires HIV-1 Nef. HIV-1 enhances PLK1 SUMOylation, causing its nuclear translocation and protein stabilization. Inhibition or knockdown of PLK1 markedly facilitates death of HIV-1-infected CD4+ T cells. Furthermore, PLK1 inhibitors strikingly reduce the size of HIV-1 latent reservoirs in primary CD4+ T cells. Our findings demonstrate that HIV-1 infection hijacks PLK1 to prevent cell death induced by viral cytopathic effects, and that PLK1 is a promising target for chemical “killing” of HIV-1 reservoir cells.

scholarly journals Ruxolitinib and Tofacitinib Are Potent and Selective Inhibitors of HIV-1 Replication and Virus ReactivationIn Vitro

2014 ◽  
Vol 58 (4) ◽  
pp. 1977-1986 ◽  
Author(s):  
Christina Gavegnano ◽  
Mervi Detorio ◽  
Catherine Montero ◽  
Alberto Bosque ◽  
Vicente Planelles ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Lymphocytes ◽  
Interleukin 2 ◽  
Similar Efficacy ◽  
Cellular Target ◽  
Immunodeficiency Virus ◽  
Targeted Inhibition ◽  
Latent Hiv ◽  
Hiv 1

ABSTRACTThe JAK-STAT pathway is activated in both macrophages and lymphocytes upon human immunodeficiency virus type 1 (HIV-1) infection and thus represents an attractive cellular target to achieve HIV suppression and reduced inflammation, which may impact virus sanctuaries. Ruxolitinib and tofacitinib are JAK1/2 inhibitors that are FDA approved for rheumatoid arthritis and myelofibrosis, respectively, but their therapeutic application for treatment of HIV infection was unexplored. Both drugs demonstrated submicromolar inhibition of infection with HIV-1, HIV-2, and a simian-human immunodeficiency virus, RT-SHIV, across primary human or rhesus macaque lymphocytes and macrophages, with no apparent significant cytotoxicity at 2 to 3 logs above the median effective antiviral concentration. Combination of tofacitinib and ruxolitinib increased the efficacy by 53- to 161-fold versus that observed for monotherapy, respectively, and each drug applied alone to primary human lymphocytes displayed similar efficacy against HIV-1 containing various polymerase substitutions. Both drugs inhibited virus replication in lymphocytes stimulated with phytohemagglutinin (PHA) plus interleukin-2 (IL-2), but not PHA alone, and inhibited reactivation of latent HIV-1 at low-micromolar concentrations across the J-Lat T cell latency model and in primary human central memory lymphocytes. Thus, targeted inhibition of JAK provided a selective, potent, and novel mechanism to inhibit HIV-1 replication in lymphocytes and macrophages, replication of drug-resistant HIV-1, and reactivation of latent HIV-1 and has the potential to reset the immunologic milieu in HIV-infected individuals.

scholarly journals Integrated Self-Inactivating Lentiviral Vectors Produce Full-Length Genomic Transcripts Competent for Encapsidation and Integration

2004 ◽  
Vol 78 (16) ◽  
pp. 8421-8436 ◽  
Author(s):  
Aaron C. Logan ◽  
Dennis L. Haas ◽  
Tal Kafri ◽  
Donald B. Kohn
Keyword(s):  
Transcriptional Activation ◽  
Transcription Initiation ◽  
Promoter Activity ◽  
Initiation Site ◽  
Full Length ◽  
Leader Region ◽  
Packaging Cell Line ◽  
Promoter Assay ◽  
Packaging Cell ◽  
Hiv 1

ABSTRACT To make human immunodeficiency virus type 1 (HIV-1)-based vectors safer for use in the research and clinical setting, a significant modification to the HIV-1 genome has been the deletion of promoter and enhancer elements from the U3 region of the long terminal repeat (LTR). Vectors containing this deletion are thought to have no LTR-directed transcription and are called self-inactivating (SIN) lentivectors. Using four distinct approaches, we show that SIN lentivectors continue to have promoter activity near the 5′ LTR, which is responsible for the production of full-length vector transcripts. To verify that transcripts derived from the LTR in SIN lentivectors are competent for encapsidation and integration, we transduced a lentiviral packaging cell line with a SIN lentivector and then observed the production of viable vector particles containing full-length SIN lentivector genomes. We have also attempted to identify sequences in the SIN lentivector which are responsible for transcriptional activation at the 5′ LTR. Using different segments of the vector LTR and leader region in a promoter assay, we have determined that the residual promoter activity is contained entirely within the leader region and that, although this element is downstream of the transcription initiation site, it is capable of initiating transcription from the 5′ end of R in the LTR. Mutation of leader region binding sites for the transcriptional activators downstream binding factor 1 (DBF1) and SP1 reduces transcription from the SIN LTR by up to 80%. Knowledge of the potential for mobilization of HIV-1-derived SIN lentivectors will be important for the design of future gene therapy trials with such vectors.

scholarly journals Broadly active zinc finger protein-guided transcriptional activation of HIV

2020 ◽  
Author(s):  
tristan Scott ◽  
Denis V O'Meally ◽  
Nicole Anne Grepo ◽  
Citradewi Soemardy ◽  
Daniel lazar ◽  
...  
Keyword(s):  
Zinc Finger ◽  
Transcriptional Activation ◽  
Zinc Finger Protein ◽  
Gene Activation ◽  
Host Cells ◽  
Finger Protein ◽  
Substantial Progress ◽  
Shock And Kill ◽  
Latent Hiv ◽  
Hiv 1

Abstract Background Human Immunodeficiency Virus type 1 (HIV-1) is a lentivirus that causes a persistent viral infection and results in the demise of immune regulatory cells. Clearance of HIV-1 infection by the immune system is inefficient, and integration of proviral DNA into the genome of host cells provides a means for evasion and long-term persistence. A therapeutic compound that specifically targets and sustainably activates a latent HIV provirus could be transformative and is an overarching goal for the “shock-and-kill” approach to a functional cure for HIV. Results Substantial progress has been made towards the development of recombinant proteins that can target specific genomic loci for gene activation, repression or inactivation by directed mutations. However, most of these modalities are too large, or too complex, for efficient therapeutic application. We describe here the development and testing of a novel recombinant zinc finger protein transactivator, ZFPb-362-VPR, which specifically and potently enhances proviral HIV transcription both in established latency models and across different viral clades. Additionally, ZFP-362-VPR activated HIV reporter gene expression in a well-established primary human CD4+ T-cell latency model and was specific in targeting the HIV LTR as determined from off-target transcriptome analyses. Conclusions: This study provides clear proof of concept for the application of a novel, and therapeutically relevant, protein transactivator to purge cellular reservoirs of HIV-1.

scholarly journals Protein Kinase D3 Is Essential for Prostratin-Activated Transcription of Integrated HIV-1 Provirus Promoter via NF-κB Signaling Pathway

2014 ◽  
Vol 2014 ◽  
pp. 1-11
Author(s):  
Huiping Wang ◽  
Xinxing Zhu ◽  
Ying Zhu ◽  
Jiangfang Liu ◽  
Xiangming Hu ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Signaling Pathway ◽  
Molecular Mechanism ◽  
Active Form ◽  
Transcription Activation ◽  
Activation Effect ◽  
Upstream Kinase ◽  
Latent Hiv ◽  
First Time ◽  
Hiv 1

Prostratin has been proposed as a promising reagent for eradicating the latent HIV-1 provirus by inducing HIV-1 transcription activation. The molecular mechanism of this activation, however, is far from clear. Here, we show that the protein kinase D3 (PKD3) is essential for prostratin-induced transcription activation of latent HIV-1 provirus. First, silencing PKD3, but not the other members of PKD family, blocked prostratin-induced transcription of HIV-1. Second, overexpressing the constitutively active form of PKD3, but not the wild-type or kinase-dead form of PKD3, augmented the expression of HIV-1. Consistent with this observation, we found that prostratin could trigger PKD3 activation by inducing the phosphorylation of its activation loop. In addition, we identified PKCεof the novel PKC subfamily as the upstream kinase for this phosphorylation. Finally, the activation effect of PKD3 on HIV-1 transcription was shown to depend on the presence ofκB element and the prostratin-induced activation of NF-κB, as indicated by the fact that silencing PKD3 blocked prostratin-induced NF-κB activation and NF-κB-dependent HIV-1 transcription. Therefore, for the first time, PKD3 is implicated in the transcription activation of latent HIV-1 provirus, and our results revealed a molecular mechanism of prostratin-induced HIV-1 transcription via PKCε/PKD3/NF-κB signaling pathway.

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