Downregulation of APOBEC3G by xenotropic murine leukemia-virus related virus (XMRV) in prostate cancer cells

<p>Abstract</p> <p>Background</p> <p>Xenotropic murine leukemia virus (MLV)-related virus (XMRV) is a gammaretrovirus that was discovered in prostate cancer tissues. Recently, it has been proposed that XMRV is a laboratory contaminant and may have originated via a rare recombination event. Host restriction factor APOBEC3G (A3G) has been reported to severely restrict XMRV replication in human peripheral blood mononuclear cells. Interestingly, XMRV infects and replicates efficiently in prostate cancer cells of epithelial origin. It has been proposed that due to lack off or very low levels of A3G protein XMRV is able to productively replicate in these cells.</p> <p>Findings</p> <p>This report builds on and challenges the published data on the absence of A3G protein in prostate epithelial cells lines. We demonstrate the presence of A3G in prostate epithelial cell lines (LNCaP and DU145) by western blot and mass spectrometry. We believe the discrepancy in A3G detection is may be due to selection and sensitivity of A3G antibodies employed in the prior studies. Our results also indicate that XMRV produced from A3G expressing LNCaP cells can infect and replicate in target cells. Most importantly our data reveal downregulation of A3G in XMRV infected LNCaP and DU145 cells.</p> <p>Conclusions</p> <p>We propose that XMRV replicates efficiently in prostate epithelial cells by downregulating A3G expression. Given that XMRV lacks accessory proteins such as HIV-1 Vif that are known to counteract A3G function in human cells, our data suggest a novel mechanism by which retroviruses can counteract the antiviral effects of A3G proteins.</p

Synthesis and anti-HIV activities of bis-(cycloSaligenyl) pronucleotides derivatives of 3′-fluoro-3′-deoxythymidine and 3′-azido-3′-deoxythymidine

Anti-HIV nucleoside monophosphates have limited cellular uptake due to the presence of negatively-charged phosphate group. Bis-(cycloSaligenyl) derivatives containing two anti-HIV nucleosides, 3′-fluoro-3′-deoxythymidine (FLT) and 3′-azido-3′-deoxythymidine (AZT) were synthesized to increase intracellular delivery of nucleoside monophosphates. 2,5-Bis(hydroxymethylene)benzene-1,4-diol was selected as a monocyclic bidentate scaffold and synthesized by three different methods from bis(hydroxymethylene)cyclohexan-1,4-diene-1,4-diol, or diethyl 2,5-dihydroxyterephthalate. The reaction of the tetraol with diisopropylphosphoramidous dichloride in the presence of 2,6-lutidine, followed by conjugation reactions with nucleosides (i.e., FLT and AZT) and oxidation afforded symmetrical and unsymmetrical bis-(cycloSaligenyl) diphosphate triester products, AZT–AZT, FLT–FLT, and FLT–AZT conjugates, in 63–74% overall yields and modest anti-HIV activities (IC50 = 2.8–69.6 μM). [Refer to PDF for graphical abstract

Therapeutic Significance of microRNA-Mediated Regulation of PARP-1 in SARS-CoV-2 Infection

The COVID-19 pandemic caused by the novel coronavirus SARS-CoV-2 (2019-nCoV) has devastated global healthcare and economies. Despite the stabilization of infectivity rates in some developed nations, several countries are still under the grip of the pathogenic viral mutants that are causing a significant increase in infections and hospitalization. Given this urgency, targeting of key host factors regulating SARS-CoV-2 life cycle is postulated as a novel strategy to counter the virus and its associated pathological outcomes. In this regard, Poly (ADP)-ribose polymerase-1 (PARP-1) is being increasingly recognized as a possible target. PARP-1 is well studied in human diseases such as cancer, central nervous system (CNS) disorders and pathology of RNA viruses. Emerging evidence indicates that regulation of PARP-1 by non-coding RNAs such as microRNAs is integral to cell survival, redox balance, DNA damage response, energy homeostasis, and several other cellular processes. In this short perspective, we summarize the recent findings on the microRNA/PARP-1 axis and its therapeutic potential for COVID-19 pathologies

Are microRNAs Important Players in HIV-1 Infection? An Update

HIV-1 has already claimed over 35 million human lives globally. No curative treatments are currently available, and the only treatment option for over 36 million people currently living with HIV/AIDS are antiretroviral drugs that disrupt the function of virus-encoded proteins. However, such virus-targeted therapeutic strategies are constrained by the ability of the virus to develop drug-resistance. Despite major advances in HIV/AIDS research over the years, substantial knowledge gaps exist in many aspects of HIV-1 replication, especially its interaction with the host. Hence, understanding the mechanistic details of virus–host interactions may lead to novel therapeutic strategies for the prevention and/or management of HIV/AIDS. Notably, unprecedented progress in deciphering host gene silencing processes mediated by several classes of cellular small non-coding RNAs (sncRNA) presents a promising and timely opportunity for developing non-traditional antiviral therapeutic strategies. Cellular microRNAs (miRNA) belong to one such important class of sncRNAs that regulate protein synthesis. Evidence is mounting that cellular miRNAs play important roles in viral replication, either usurped by the virus to promote its replication or employed by the host to control viral infection by directly targeting the viral genome or by targeting cellular proteins required for productive virus replication. In this review, we summarize the findings to date on the role of miRNAs in HIV-1 biology

Correction: Cocaine Enhances HIV-1 Replication in CD4+ T Cells by Down-Regulating MiR-125b.

[This corrects the article DOI: 10.1371/journal.pone.0051387.]

Cocaine enhances HIV-1 replication in CD4+ T cells by down-regulating MiR-125b.

The main objective of this study was to examine effects of cocaine on HIV-1 replication in primary CD4+ T cells. Cocaine a commonly used drug among HIV-1 positive individuals serves as a cofactor for HIV-1 infection and progression to acquired immunodeficiency syndrome (AIDS). Accumulating evidence suggest that cocaine increases HIV-1 replication in cell cultures, peripheral blood mononuclear cells (PBMCs) and animal models. Intriguingly, there are no studies on cocaine-induced alterations in HIV-1 replication in primary CD4+ T cells that serve as the main targets for HIV-1 replication in vivo. In this report, we demonstrate cocaine-induced enhancement of HIV-1 replication in primary CD4+ T cells isolated from human PBMCs. To decipher a potential mechanism, we examined whether cocaine targets the innate antiviral immunity of CD4+ T cells mediated by cellular microRNAs (miRNAs). This is because recently a network of anti-HIV miRNAs in CD4+ T cells is highlighted to suppress viral replication. Our genome wide miRNA expression analysis indicated downregulation of several anti-HIV miRNAs (miR-28, miR-125b, miR-150, miR-223, and miR-382) in cocaine treated CD4+ T cells. However, our real-time quantitative PCR analysis revealed significant downregulation of miR-125b only. Our results illustrated that miR-125b knockdown enhances HIV-1 replication, whereas overexpression of miR-125b decreases HIV-1 replication in these cells. Therefore, we believe miR-125b is a key player for the cocaine induced enhancement of HIV-1 replication in CD4+ T cells. Since, miR-125b targets the 3' UTR regions of HIV-1 transcripts and inhibits viral protein translation, our data suggest modulation of post entry steps of HIV-1 by cocaine. Given that a plethora of studies suggest that cocaine regulates HIV entry, our results implicate a potentially novel mechanism by which cocaine can increase viral replication in CD4+ T cells

Cocaine regulates transcription of miR-125b.

<p>(A) A schematic representation of miR-125b promoter construct used. In this construct the miR-125b promoter drives the luciferase gene. (<b>B</b>) A construct containing miR-125b promoter driven luciferase gene or the vector control were transfected into 293T cells by Lipofectamine transfection. After 24 hrs, these cells were treated with cocaine (0.1 µM and 1 µM) for 4 hrs. Thereafter, cells were lysed and luciferase activity was measured by a luminometer. Cocaine treatment decreased miR-125b driven luciferase expression. Data are representative of three independent experiments conducted in triplicates.</p

Cocaine induced downregulation of miR-125b enhances HIV-1 replication.

<p>We carried out single cycle replication assay to evaluate modulation of HIV-1 replication by cocaine. For this experiment we used a T cell line SupT1 that expresses miR-125b. (<b>A</b>) Cocaine treatment substantially downregulated miR-125b in SupT1 cells as determined by real time PCR. Pseudotyped HIV-1 virions with RFP reporter were used to infect SupT1 cells and HIV-1 replication was measured by detecting RFP expression by FACS 48–72 hr post infection. (<b>B</b>) RFP expression of uninfected cells. HIV-1 replication was measured in the absence (<b>C</b>) and presence (<b>D</b>) of cocaine. (<b>E</b>) Relative RFP expression from three independent experiments. Cocaine treatment resulted in increased RFP expression implying enhanced HIV-1 replication. Data are representative of three independent experiments conducted in triplicates.</p

Cocaine-enhances HIV-1 replication in primary CD4+ T cells.

<p>Primary CD4+ T cells were isolated by negative selection from human PBMCs. After isolation, these cells were activated by PHA for 48–72 hrs and infected with infectious HIV-1 LAI by spinoculation and cultured in the presence or absence of cocaine. Productive infection was measured by detecting viral p24 protein 7 days post infection by FACS. (A–B) Representative data from two donors. Panels I: p24 staining of uninfected cells. Panels II: p24 staining of HIV-1 infected cells in the absence cocaine. Panels III: p24 staining of HIV-1 infected cells in the presence of cocaine. (C) Data from ten donors with fold increase in HIV-1 replication in presence of cocaine. Cocaine treatment significantly increased the percentage of cells expressing viral p24 protein in these cells. Data are representative of three independent experiments comprising nine different donors.</p