Isolation of a cellular factor that can reactivate latent HIV-1 without T cell activation

Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 04/2009; 106(15):6321-6. DOI: 10.1073/pnas.0809536106
Source: PubMed


HIV-1 latency in resting CD4(+) T cells represents a major barrier to virus eradication in patients on highly active antiretroviral therapy (HAART). Eliminating the latent HIV-1 reservoir may require the reactivation of viral gene expression in latently infected cells. Most approaches for reactivating latent HIV-1 require nonspecific T cell activation, which has potential toxicity. To identify factors for reactivating latent HIV-1 without inducing global T cell activation, we performed a previously undescribed unbiased screen for genes that could activate transcription from the HIV-1 LTR in an NF-kappaB-independent manner, and isolated an alternatively spliced form of the transcription factor Ets-1, DeltaVII-Ets-1. DeltaVII-Ets-1 activated HIV-1 transcription through 2 conserved regions in the LTR, and reactivated latent HIV-1 in cells from patients on HAART without causing significant T cell activation. Our results highlight the therapeutic potential of cellular factors for the reactivation of latent HIV-1 and provide an efficient approach for their identification.

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    • "Combining prostratin, a non-tumorigenic phorbol ester, and histone deacetylase (HDAC) inhibitors have been suggested as an effective way to purge the latent reservoir [3]. Reactive oxygen species activators that stimulate latent HIV transcription without the undesirable effects of global T-cell activation have also been described [4], [5]. Of note, both of these strategies involve the induction of NF-κB. "
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    ABSTRACT: Attempts to eradicate HIV have been thwarted by the persistence of a small pool of quiescent memory CD4 T cells that harbor a transcriptionally silent, integrated form of the virus that can produce infectious virions following an anamnestic immune response. Transcription factors downstream of T-cell receptor activation, such as NF-κB/Rel and nuclear factor of activated T cells (NFAT) transcription members, are considered important regulators of HIV transcription during acute HIV infection. We now report studies exploring their precise role as antagonists of HIV latency using cell and primary CD4 T cell models of HIV-1 latency. Surprisingly, RNA interference studies performed in J-Lat CD4 T cells suggested that none of the NFATs, including NFATc1, NFATc2, NFATc3, and NFAT5, played a key role in the reactivation of latent HIV. However, cyclosporin A markedly inhibited the reactivation response. These results were reconciled when calcium signaling through calcineurin was shown to potentiate prostratin induced activation of NF-κB that in turn stimulated the latent HIV long terminal repeat (LTR). Similar effects of calcineurin were confirmed in a primary CD4 T cell model of HIV latency. These findings highlight an important role for calcineurin in NF-κB-dependent induction of latent HIV transcription. Innovative approaches exploiting the synergistic actions of calcineurin and prostratin in the absence of generalized T-cell activation merit exploration as a means to attack the latent viral reservoir.
    Full-text · Article · Oct 2013 · PLoS ONE
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    • "ng with phosphorylation of the transcription factor ETS - 1 ( pS282 / pS285 ) , a well - characterized substrate of CaMKII that has been linked to HIV - 1 gene expression ( Sieweke et al . , 1998 ; Soderling , 1999 ; Yang et al . , 2009 ) . In addition , overex - pression of a splice variant of ETS - 1 lacking exon VII reactivated latent HIV - 1 ( Yang et al . , 2009 ) . Interestingly , exon VII contains serines 282 and 285 , and the ETS - 1 isoform lacking this exon binds to DNA more strongly than wild - type ETS - 1 independently of CaMKII activity ( Fisher et al . , 1994 ) ."
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    ABSTRACT: Receptor engagement by HIV-1 during host cell entry activates signaling pathways that can reprogram the cell for optimal viral replication. To obtain a global view of the signaling events induced during HIV-1 entry, we conducted a quantitative phosphoproteomics screen of primary human CD4(+) T cells after infection with an HIV-1 strain that engages the receptors CD4 and CXCR4. We quantified 1,757 phosphorylation sites with high stringency. The abundance of 239 phosphorylation sites from 175 genes, including several proteins in pathways known to be impacted by HIV-receptor binding, changed significantly within a minute after HIV-1 exposure. Several previously uncharacterized HIV-1 host factors were also identified and confirmed through RNAi depletion studies. Surprisingly, five serine/arginine-rich (SR) proteins involved in messenger RNA splicing, including the splicing factor SRm300 (SRRM2), were differentially phosophorylated. Mechanistic studies with SRRM2 suggest that HIV-1 modulates host cell alternative splicing machinery during entry in order to facilitate virus replication and release.
    Preview · Article · May 2013 · Cell host & microbe
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    • "The combination of TSA (an HDACI) and TNF-α (NF-κB inducer) synergistically activates the HIV-1 promoter. However, toxicity of these compounds undermines their clinical interest for HIV-1 therapy [184]. Although promising results in the reduction of HIV-1 reservoirs were reported using HDAC inhibitor VPA (valproic acid), more recent studies did not confirm these results [185, 186]. "
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    ABSTRACT: The introduction of highly active antiretroviral therapy (HAART) has been an important breakthrough in the treatment of HIV-1 infection and has also a powerful tool to upset the equilibrium of viral production and HIV-1 pathogenesis. Despite the advent of potent combinations of this therapy, the long-lived HIV-1 reservoirs like cells from monocyte-macrophage lineage and resting memory CD4+ T cells which are established early during primary infection constitute a major obstacle to virus eradication. Further HAART interruption leads to immediate rebound viremia from latent reservoirs. This paper focuses on the essentials of the molecular mechanisms for the establishment of HIV-1 latency with special concern to present and future possible treatment strategies to completely purge and target viral persistence in the reservoirs.
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