Expression of an RNA glycosidase inhibits HIV-1 transactivation of transcription

2017 ◽  
Vol 474 (20) ◽  
pp. 3471-3483 ◽  
Author(s):  
Meherzad Kutky ◽  
Katalin A. Hudak
Keyword(s):  
Mechanistic Explanation ◽  
Viral Rna ◽  
Mrna Levels ◽  
Activator Protein 1 ◽  
Tat Protein ◽  
Antiviral Protein ◽  
Jnk Pathway ◽  
Culture Cells ◽  
Virus Transcription ◽  
Hiv 1

HIV-1 (human immunodeficiency virus) transcription is primarily controlled by the virally encoded Tat (transactivator of transcription) protein and its interaction with the viral TAR (transcription response element) RNA element. Specifically, binding of a Tat-containing complex to TAR recruits cellular factors that promote elongation of the host RNA polymerase engaging the viral DNA template. Disruption of this interaction halts viral RNA transcription. In the present study, we investigated the effect of pokeweed antiviral protein (PAP), an RNA glycosidase (EC#: 3.2.2.22) synthesized by the pokeweed plant (Phytolacca americana), on transcription of HIV-1 mRNA. We show that co-expression of PAP with a proviral clone in culture cells resulted in a Tat-dependent decrease in viral mRNA levels. PAP reduced HIV-1 transcriptional activity by inhibiting Tat protein synthesis. The effects of PAP expression on host factors AP-1 (activator protein 1), NF-κB (nuclear factor kappa-light-chain-enhancer of activated B-cells) and specificity protein 1, which modulate HIV-1 transcription by binding to the viral LTR (5′-long terminal repeat), were also investigated. Only AP-1 showed a modest JNK pathway-dependent increase in activity in the presence of PAP; however, this activation was not sufficient to significantly enhance transcription from a partial viral LTR containing AP-1 binding sites. Therefore, the primary effect of PAP on HIV-1 transcription is to reduce viral RNA synthesis by decreasing the abundance of Tat. These findings provide a mechanistic explanation for the observed decrease in viral RNAs in cells expressing PAP and contribute to our understanding of the antiviral effects of this plant protein.

scholarly journals KHNYN is essential for ZAP-mediated restriction of HIV-1 containing clustered CpG dinucleotides

2019 ◽  
Author(s):  
Mattia Ficarelli ◽  
Harry Wilson ◽  
Rui Pedro Galão ◽  
Stuart J D Neil ◽  
Chad M Swanson
Keyword(s):  
Infectious Virus ◽  
Rna Virus ◽  
Virus Production ◽  
Innate Immune ◽  
Viral Rna ◽  
Antiviral Protein ◽  
Cpg Dinucleotides ◽  
Endonuclease Domain ◽  
Virus Genomes ◽  
Hiv 1

AbstractCpG dinucleotides are suppressed in most vertebrate RNA viruses, including HIV-1, and introducing CpGs into RNA virus genomes inhibits their replication. The zinc-finger antiviral protein (ZAP) binds regions of viral RNA containing CpGs and targets them for degradation. ZAP does not have enzymatic activity and recruits other cellular proteins to inhibit viral replication. Here we show that KHNYN, a protein with no previously known function, interacts with ZAP. KHNYN overexpression selectively inhibits HIV-1 containing clustered CpG dinucleotides and this requires ZAP and its cofactor TRIM25. KHNYN requires both its KH-like domain and NYN endonuclease domain for antiviral activity. Crucially, depletion of KHNYN eliminated the deleterious effect of CpG dinucleotides on HIV-1 RNA abundance and infectious virus production indicating that KHNYN is required for this antiviral pathway. Overall, we have identified KHNYN as a novel ZAP cofactor that is essential for innate immune destruction of CpG containing viral RNA.

scholarly journals Long Noncoding RNA uc002yug.2 Activates HIV-1 Latency through Regulation of mRNA Levels of Various RUNX1 Isoforms and Increased Tat Expression

2018 ◽  
Vol 92 (9) ◽  
Author(s):  
Chen Huan ◽  
Zhaolong Li ◽  
Shanshan Ning ◽  
Hong Wang ◽  
Xiao-Fang Yu ◽  
...  
Keyword(s):  
Noncoding Rna ◽  
Therapeutic Interventions ◽  
Viral Reservoir ◽  
Mrna Levels ◽  
Tat Protein ◽  
Latent Viral Reservoir ◽  
Latently Infected ◽  
Primary Obstacle ◽  
Latent Hiv ◽  
Hiv 1

ABSTRACT The HIV-1 reservoir is a major obstacle to complete eradication of the virus. Although many proteins and RNAs have been characterized as regulators in HIV-1/AIDS pathogenesis and latency, only a few long noncoding RNAs (lncRNAs) have been shown to be closely associated with HIV-1 replication and latency. In this study, we demonstrated that lncRNA uc002yug.2 plays a key role in HIV-1 replication and latency. uc002yug.2 potentially enhances HIV-1 replication, long terminal repeat (LTR) activity, and the activation of latent HIV-1 in both cell lines and CD4 + T cells from patients. Further investigation revealed that uc002yug.2 activates latent HIV-1 through downregulating RUNX1b and -1c and upregulating Tat protein expression. The accumulated evidence supports our model that the Tat protein has the key role in the uc002yug.2-mediated regulatory effect on HIV-1 reactivation. Moreover, uc002yug.2 showed an ability to activate HIV-1 similar to that of suberoylanilide hydroxamic acid or phorbol 12-myristate 13-acetate using latently infected cell models. These findings improve our understanding of lncRNA regulation of HIV-1 replication and latency, providing new insights into potential targeted therapeutic interventions. IMPORTANCE The latent viral reservoir is the primary obstacle to curing HIV-1 disease. To date, only a few lncRNAs, which play major roles in various biological processes, including viral infection, have been identified as regulators in HIV-1 latency. In this study, we demonstrated that lncRNA uc002yug.2 is important for both HIV-1 replication and activation of latent viruses. Moreover, uc002yug.2 was shown to activate latent HIV-1 through regulating alternative splicing of RUNX1 and increasing the expression of Tat protein. These findings highlight the potential merit of targeting lncRNA uc002yug.2 as an activating agent for latent HIV-1.

scholarly journals Selectively Reduced tat mRNA Heralds the Decline in Productive Human Immunodeficiency Virus Type 1 Infection in Monocyte-Derived Macrophages

2002 ◽  
Vol 76 (24) ◽  
pp. 12611-12621 ◽  
Author(s):  
Secondo Sonza ◽  
Helen P. Mutimer ◽  
Kate O'Brien ◽  
Philip Ellery ◽  
Jane L. Howard ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Virus Production ◽  
Productive Infection ◽  
Mrna Levels ◽  
Tat Protein ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The transcription and splicing of human immunodeficiency virus type 1 (HIV-1) mRNA in primary blood monocyte-derived macrophages (MDM) and CD4+ peripheral blood lymphocytes (PBL) were compared to determine whether any differences might account for the slower noncytopathic infection of cells of the macrophage lineage. The expression of regulatory mRNAs during acute infection of MDM was delayed by about 12 h compared to that of PBL. In each cell type, an increase in spliced viral mRNAs slightly preceded virus production from the culture. Following the peak of productive infection, there was a proportional decrease in the expression of all regulatory mRNAs detected in PBL. In MDM, a dramatic additional decrease specifically in the tat mRNA species heralded a reduction in virus production. This decline in tat mRNA was reflected by a concomitant decrease in Tat activity in the cells and occurred with the same kinetics irrespective of the age of the cells when infected. Addition of exogenous Tat protein elicited a burst of virus production from persistently infected MDM, suggesting that the decrease in virus production from the cultures is a consequence of the reduction in tat mRNA levels. Our results show that modulation of HIV-1 mRNAs in macrophages during long-term infection, which is dependent on the period of infection rather than cell differentiation or maturation, results in a selective reduction of Tat protein levels at the commencement of a persistent, less productive phase of infection. Determination of the mechanism of this mRNA modulation may lead to novel targets for control of replication in these important viral reservoirs.

scholarly journals Cellular Factors Targeting HIV-1 Transcription and Viral RNA Transcripts

Viruses ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 495
Author(s):  
Rayhane Nchioua ◽  
Matteo Bosso ◽  
Dorota Kmiec ◽  
Frank Kirchhoff
Keyword(s):  
Defense Mechanisms ◽  
Viral Gene Expression ◽  
Immune Defense ◽  
Viral Rna ◽  
Viral Gene ◽  
Restriction Factors ◽  
Antiviral Protein ◽  
Rna Transcripts ◽  
Cellular Factors ◽  
Hiv 1

Restriction factors are structurally and functionally diverse cellular proteins that constitute a first line of defense against viral pathogens. Exceptions exist, but typically these proteins are upregulated by interferons (IFNs), target viral components, and are rapidly evolving due to the continuous virus–host arms race. Restriction factors may target HIV replication at essentially each step of the retroviral replication cycle, and the suppression of viral transcription and the degradation of viral RNA transcripts are emerging as major innate immune defense mechanisms. Recent data show that some antiviral factors, such as the tripartite motif-containing protein 22 (TRIM22) and the γ-IFN-inducible protein 16 (IFI16), do not target HIV-1 itself but limit the availability of the cellular transcription factor specificity protein 1 (Sp1), which is critical for effective viral gene expression. In addition, several RNA-interacting cellular factors including RNAse L, the NEDD4-binding protein 1 (N4BP1), and the zinc finger antiviral protein (ZAP) have been identified as important immune effectors against HIV-1 that may be involved in the maintenance of the latent viral reservoirs, representing the major obstacle against viral elimination and cure. Here, we review recent findings on specific cellular antiviral factors targeting HIV-1 transcription or viral RNA transcripts and discuss their potential role in viral latency.

scholarly journals HIV-1 Tat Protein-Induced Alterations of ZO-1 Expression are Mediated by Redox-Regulated ERK1/2 Activation

2005 ◽  
Vol 25 (10) ◽  
pp. 1325-1335 ◽  
Author(s):  
Hong Pu ◽  
Jing Tian ◽  
Ibolya E Andras ◽  
Kentaro Hayashi ◽  
Govinder Flora ◽  
...  
Keyword(s):  
Specific Inhibitor ◽  
Inflammatory Cells ◽  
Mrna Levels ◽  
Tat Protein ◽  
Extracellular Signal ◽  
Junction Protein ◽  
The Central Nervous System ◽  
The Right ◽  
The Brain ◽  
Hiv 1

HIV-1 Tat protein plays an important role in inducing monocyte infiltration into the brain and may alter the structure and functions of the blood—brain barrier (BBB). The BBB serves as a frontline defense system, protecting the central nervous system from infected monocytes entering the brain. Therefore, the aim of the present study was to examine the mechanisms of Tat effect on the integrity of the BBB in the mouse brain. Tat was injected into the right hippocampi of C57BL/6 mice and expression of tight junction protein zonula occludens-1 (ZO-1) was determined in control and treated mice. Tat administration resulted in decreased mRNA levels of ZO-1 and marked disruption of ZO-1 continuity. These changes were associated with accumulation of inflammatory cells in brain tissue of Tat-treated mice. Further experiments indicated that Tat-mediated alterations of redox-related signaling may be responsible for decreased ZO-1 expression. Specifically, injections with Tat resulted in activation of extracellular signal-regulated kinase 1/2 (ERK1/2) and pretreatment with U0126, a specific inhibitor of ERK kinase, effectively ameliorated the Tat-induced diminished ZO-1 levels. In addition, administration of N-acetylcysteine (NAC), a precursor of glutathione and a potent antioxidant, attenuated both Tat-induced ERK1/2 activation and alterations in ZO-1 expression. These results indicate that Tat-induced oxidative stress can play an important role in affecting the integrity of the BBB through the ERK1/2 pathway.

scholarly journals Analysis of Tat protein characteristics in human immunodeficiency virus type 1 sub-subtype A6 (Retroviridae: Orthoretrovirinae: Lentivirus: Human immunodeficiency virus-1)

2022 ◽  
Vol 66 (6) ◽  
pp. 452-464
Author(s):  
A. I. Kuznetsova ◽  
K. B. Gromov ◽  
D. E. Kireev ◽  
A. V. Shlykova ◽  
A. E. Lopatukhin ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Tat Protein ◽  
International Database ◽  
Virus Transcription ◽  
Subtype B ◽  
Immunodeficiency Virus ◽  
Hiv Type 1 ◽  
Characteristic Features ◽  
Hiv 1

Introduction. Tat protein is a major factor of HIV (human immunodeficiency virus) transcription regulation and has other activities. Tat is characterized by high variability, with some amino acid substitutions, including subtypespecific ones, being able to influence on its functionality. HIV type 1 (HIV-1) sub-subtype A6 is the most widespread in Russia. Previous studies of the polymorphisms in structural regions of the A6 variant have shown numerous characteristic features; however, Tat polymorphism in A6 has not been studied.Goals and tasks. The main goal of the work was to analyze the characteristics of Tat protein in HIV-1 A6 variant, that is, to identify substitutions characteristic for A6 and A1 variants, as well as to compare the frequency of mutations in functionally significant domains in sub-subtype A6 and subtype B.Material and methods. The nucleotide sequences of HIV-1 sub-subtypes A6, A1, A2, A3, A4, subtype B and the reference nucleotide sequence were obtained from the Los Alamos international database.Results and discussion. Q54H and Q60H were identified as characteristic substitutions. Essential differences in natural polymorphisms between sub-subtypes A6 and A1 have been demonstrated. In the CPP-region, there were detected mutations (R53K, Q54H, Q54P, R57G) which were more common in sub-subtype A6 than in subtype B.Conclusion. Tat protein of sub-subtype A6 have some characteristics that make it possible to reliably distinguish it from other HIV-1 variants. Mutations identified in the CPP region could potentially alter the activity of Tat. The data obtained could form the basis for the drugs and vaccines development.

scholarly journals Rho-kinase inhibitor hydroxyfasudil protects against HIV-1 Tat-induced dysfunction of tight junction and neprilysin/Aβ transfer receptor expression in mouse brain microvessels

2021 ◽  
Vol 476 (5) ◽  
pp. 2159-2170
Author(s):  
Qiangtang Chen ◽  
Yu Wu ◽  
Yachun Yu ◽  
Junxiang Wei ◽  
Wen Huang
Keyword(s):  
Tight Junction ◽  
Signaling Pathway ◽  
Mouse Brain ◽  
Kinase Inhibitor ◽  
Rho Kinase ◽  
Receptor Expression ◽  
Mrna Levels ◽  
Brain Microvessels ◽  
Rho Kinase Inhibitor ◽  
Hiv 1

AbstractHIV-1 transactivator protein (Tat) induces tight junction (TJ) dysfunction and amyloid-beta (Aβ) clearance dysfunction, contributing to the development and progression of HIV-1-associated neurocognitive disorder (HAND). The Rho/ROCK signaling pathway has protective effects on neurodegenerative disease. However, the underlying mechanisms of whether Rho/ROCK protects against HIV-1 Tat-caused dysfunction of TJ and neprilysin (NEP)/Aβ transfer receptor expression have not been elucidated. C57BL/6 mice were administered sterile saline (i.p., 100 μL) or Rho-kinase inhibitor hydroxyfasudil (HF) (i.p., 10 mg/kg) or HIV-1 Tat (i.v., 100 μg/kg) or HF 30 min before being exposed to HIV-1 Tat once a day for seven consecutive days. Evans Blue (EB) leakage was detected via spectrophotometer and brain slides in mouse brains. The protein and mRNA levels of zonula occludens-1 (ZO-1), occludin, NEP, receptor for advanced glycation end products (RAGE), and low-density lipoprotein receptor-related protein 1 (LRP1) in mouse brain microvessels were, respectively, analyzed by Western blotting and quantitative real-time polymerase chain reaction (qRT-PCR) analyses. Exposure of the mice to HIV-1 Tat increased the amount of EB leakage, EB fluorescence intensity, blood–brain barrier (BBB) permeability, as well as the RAGE protein and mRNA levels, and decreased the protein and mRNA levels of ZO-1, occludin, NEP, and LRP1 in mouse brain microvessels. However, these effects were weakened by Rho-kinase inhibitor HF. Taken together, these results provide information that the Rho/ROCK signaling pathway is involved in HIV-1 Tat-induced dysfunction of TJ and NEP/Aβ transfer receptor expression in the C57BL/6 mouse brain. These findings shed some light on potentiality of inhibiting Rho/Rock signaling pathway in handling HAND.

HIV-1 tat protein expression in mouse brain potentiates ethanol reward and reinstates extinguished ethanol-seeking behavior

2014 ◽  
Vol 140 ◽  
pp. e141-e142
Author(s):  
Jay P. McLaughlin ◽  
M.L. Ganno ◽  
S.O. Eans ◽  
Jason J. Paris ◽  
H.D. Singh
Keyword(s):  
Protein Expression ◽  
Mouse Brain ◽  
Tat Protein ◽  
Seeking Behavior ◽  
Hiv 1
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