Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York 14642, USA.
J Biol Chem. 2012 Jun 22;287(26):21570-4. doi: 10.1074/jbc.C112.374843. Epub 2012 May 14.
Recently, SAMHD1 has come under intense focus as a host anti-HIV factor. SAMHD1 is a dNTP triphosphohydrolase, which leads to the regulation of DNA metabolism in host cells. HIV-2/SIV (simian immunodeficiency virus) viral protein x (Vpx) has been shown to promote the degradation of SAMHD1. In this study, we examine the kinetics of SAMHD1 degradation, the increase in the dNTP pool level, and the efficiency of proviral DNA synthesis in Vpx+ virus-like particle (VLP)-treated monocyte-derived macrophages (MDMs). Our results indicate a very close temporal link with a reduction in SAMHD1 detected within the first few hours of Vpx+ VLP treatment. This loss of SAMHD1 is followed by a significant increase in cellular dNTP levels by 8 h after Vpx+ VLP addition, ultimately leading to the enhancement of the HIV proviral DNA synthesis rate and HIV infection in MDMs. Finally, the pretreatment of MDMs with the Vpx+ VLPs, which is a widely used protocol, displayed identical proviral DNA synthesis as compared with MDMs co-treated with Vpx+ VLP and HIV vector. These findings further indicate that Vpx degradation of SAMHD1 is sufficiently rapid to enable appropriate progression of reverse transcription in MDMs, even when present at the time of infection. Overall, this study demonstrates a tight interplay between SAMHD1 level, dNTP levels, and HIV proviral DNA synthesis kinetics in MDMs.
最近，SAMHD1 作为一种宿主抗 HIV 因子受到了广泛关注。SAMHD1 是一种 dNTP 三磷酸水解酶，可调节宿主细胞中的 DNA 代谢。已经证明 HIV-2/SIV（猴免疫缺陷病毒）病毒蛋白 x（Vpx）可促进 SAMHD1 的降解。在这项研究中，我们研究了 SAMHD1 降解的动力学、dNTP 池水平的增加以及 Vpx+病毒样颗粒（VLP）处理的单核细胞衍生巨噬细胞（MDM）中前病毒 DNA 合成的效率。我们的结果表明，Vpx+ VLP 处理后最初几个小时内检测到 SAMHD1 减少与时间非常接近。这种 SAMHD1 的丢失随后导致细胞内 dNTP 水平在 Vpx+ VLP 添加 8 小时后显著增加，最终导致 HIV 前病毒 DNA 合成率和 MDM 中的 HIV 感染增强。最后，用 Vpx+ VLPs 预处理 MDM（这是一种广泛使用的方案），与用 Vpx+ VLP 和 HIV 载体共处理的 MDM 相比，显示出相同的前病毒 DNA 合成。这些发现进一步表明，Vpx 降解 SAMHD1 的速度足够快，即使在感染时，也能使 MDM 中的逆转录适当进行。总的来说，这项研究表明，SAMHD1 水平、dNTP 水平和 MDM 中 HIV 前病毒 DNA 合成动力学之间存在紧密的相互作用。
