Anti-HIV Host Factor SAMHD1 Regulates Viral Sensitivity to Nucleoside Reverse Transcriptase Inhibitors via Modulation of Cellular dNTP Levels.

University of Rochester Medical Center, United States
Journal of Biological Chemistry (Impact Factor: 4.6). 06/2013; DOI: 10.1074/jbc.M113.472159
Source: PubMed

ABSTRACT Newly identified anti-HIV host factor, SAMHD1, restricts replication of lentiviruses such as HIV-1, HIV-2, and SIV in macrophages by enzymatically hydrolyzing and depleting cellular dNTPs, which are the substrates of viral DNA polymerases. HIV-2 and some SIVs express Vpx, which counteracts SAMHD1 and elevates cellular dNTPs, enhancing viral replication in macrophages. Since nucleoside reverse transcriptase inhibitors (NRTIs), the most commonly used anti-HIV drugs, compete against cellular dNTPs for incorporation into proviral DNA, we tested whether SAMHD1 directly affects the efficacy of NRTIs in inhibiting HIV-1. We found that reduction of SAMHD1 levels with the use of virus-like particles (VLPs) expressing Vpx and SAMHD1 specific shRNA, subsequently elevates cellular dNTPs and significantly decreases HIV-1 sensitivity to various NRTIs in macrophages. However, VLP +Vpx treatment of activated CD4+ T cells only minimally reduced NRTI efficacy. Furthermore, our HPLC-based assay could not detect SAMHD1-mediated hydrolysis of various NRTI-triphosphates tested in this study, suggesting that the reduced sensitivity of HIV-1 to NRTIs upon SAMHD1 degradation is most likely caused by the elevation of the cellular dNTP levels.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Human immunodeficiency virus type 2 (HIV-2) infects about 2 million people worldwide. HIV-2 has fewer treatment options than HIV-1, yet may evolve drug resistance more quickly. We have analyzed several novel drugs for anti-HIV-2 activity. It was observed that 5-azacytidine, clofarabine, gemcitabine and resveratrol have potent anti-HIV-2 activity. The EC50 values for 5-azacytidine, clofarabine and resveratrol were found to be significantly lower with HIV-2 compared to that of HIV-1. A time-of-addition assay was used to analyze the ability of these drugs to interfere with HIV-2 replication. Reverse transcription was the likely target for antiretroviral activity. Taken together, several novel drugs have been discovered to have activity against HIV-2. Based upon their known activities, these drugs may elicit enhanced HIV-2 mutagenesis and therefore be useful for inducing HIV-2 lethal mutagenesis. In addition, the data are consistent with HIV-2 reverse transcriptase (RT) being more sensitive than HIV-1 RT to dNTP pool alterations.
    Journal of General Virology 08/2014; DOI:10.1099/vir.0.069864-0 · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The eradication of HIV necessitates elimination of the HIV latent reservoir. Identifying host determinants governing latency and reservoir size in the setting of antiretroviral therapy (ART) is an important step in developing strategies to cure HIV infection. We sought to determine the impact of cell-intrinsic immunity on the HIV latent reservoir. We investigated the relevance of a comprehensive panel of established anti-HIV-1 host restriction factors to multiple established virologic and immunologic measures of viral persistence in HIV-1-infected, ART-suppressed individuals. We measured the mRNA expression of 42 anti-HIV-1 host restriction factors, levels of cell-associated HIV-1 RNA, levels of total pol and 2-long terminal repeat (2-LTR) circle HIV-1 DNA and immunophenotypes of CD4 T cells in 72 HIV-1-infected individuals on suppressive ART (23 individuals initiated ART less than 1 year postinfection, and 49 individuals initiated ART greater than 1 year post-infection). Correlations were analysed using nonparametric tests. The enhanced expression of a few select host restriction factors, p21, schlafen 11 and PAF1, was strongly associated with reduced CD4 T-cell associated HIV RNA during ART (P < 0.001). In addition, our data suggested that ART perturbs the regulatory relationship between CD4 T-cell activation and restriction factor expression. Lastly, cell-intrinsic immune responses were significantly enhanced in individuals who initiated ART during early versus chronic infection and may contribute to the reduced reservoir size observed in these individuals. Intrinsic immune responses modulate HIV persistence during suppressive ART and may be manipulated to enhance the efficacy of ART and promote viral eradication through reversal of latency in vivo.
    AIDS (London, England) 01/2015; 29(4). DOI:10.1097/QAD.0000000000000572 · 6.56 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: For >35 yr, we have known that the accuracy of DNA replication is controlled in large part by the relative concentrations of the 4 canonical deoxyribonucleoside 5'-triphosphates (dNTPs) at the replisome. Since this field was last reviewed, ∼8 yr ago, there has been increased understanding of the mutagenic pathways as they occur in living cells. At the same time, aspects of deoxyribonucleotide metabolism have been shown to be critically involved in processes as diverse as cell cycle control, protooncogene expression, cellular defense against HIV infection, replication rate control, telomere length control, and mitochondrial function. Evidence supports a relationship between dNTP pools and microsatellite repeat instability. Relationships between dNTP synthesis and breakdown in controlling steady-state pools have become better defined. In addition, new experimental approaches have allowed definitive analysis of mutational pathways induced by dNTP pool abnormalities, both in Escherichia coli and in yeast. Finally, ribonucleoside triphosphate (rNTP) pools have been shown to be critical determinants of DNA replication fidelity. These developments are discussed in this review article.-Mathews, C. K. Deoxyribonucleotides as genetic and metabolic regulators.
    The FASEB Journal 06/2014; 28(9). DOI:10.1096/fj.14-251249 · 5.48 Impact Factor

Similar Publications