Zhang Hong-Sheng, Wu Tong-Chao, Sang Wei-Wei, Ruan Zheng
College of Life Science and Bioengineering, Beijing University of Technology, Pingleyuan 100#, District of Chaoyang, Beijing, China.
Biochim Biophys Acta. 2012 May;1823(5):1017-23. doi: 10.1016/j.bbamcr.2012.02.014. Epub 2012 Mar 3.
MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression and may contribute to the development and progression of many infective diseases including human immunodeficiency virus 1 (HIV-1) infection. The Tat protein is fundamental to viral gene expression. In this study, our goal was to investigate the regulation of a specific miRNA (known as miR-217) in multinuclear activation of galactosidase indicator (MAGI) cells and explore the mechanisms by which miR-217 influenced Tat-induced HIV-1 transactivation through down-regulation of SIRT1 expression. We showed that miR-217 was up-regulated when Tat was expressed in multinuclear activation of galactosidase indicator cells. Forced expression of "miR-217 mimics" increased Tat-induced LTR transactivation. In addition, miR-217 significantly inhibited SIRT1 protein expression by acting on the 3'-UTR of the SIRT1 mRNA. In turn, the decrease in SIRT1 protein abundance provoked by miR-217 affected two important types of downstream signaling molecules that were regulated by Tat. Lower expression of SIRT1 caused by miR-217 enhanced Tat-induced phosphorylation of IKK and p65-NFkB and also exacerbated the loss of AMPK phosphorylation triggered by Tat. Our results uncover previously unknown links between Tat and a specific host cell miRNA that targets SIRT1. We also demonstrate that this regulatory mechanism impinges on p65-NFkB and AMPK signaling: two important host cell pathways that influence HIV-1 pathogenesis. Our results also suggest that strategies to augment SIRT1 protein expression by down-regulation of miR-217 may have therapeutic benefits to prevent HIV-1 replication.
微小RNA（miRNA）是一类小的非编码RNA，可调节基因表达，并可能在包括人类免疫缺陷病毒1型（HIV-1）感染在内的许多感染性疾病的发生和发展中发挥作用。Tat蛋白对于病毒基因表达至关重要。在本研究中，我们的目标是研究特定miRNA（即miR-217）在半乳糖苷酶指示细胞（MAGI）多核激活中的调控作用，并探讨miR-217通过下调SIRT1表达影响Tat诱导的HIV-1反式激活的机制。我们发现，当Tat在半乳糖苷酶指示细胞的多核激活中表达时，miR-217会上调。“miR-217模拟物”的强制表达增加了Tat诱导的LTR反式激活。此外，miR-217通过作用于SIRT1 mRNA的3'-UTR显著抑制SIRT1蛋白表达。反过来，miR-217引起的SIRT1蛋白丰度降低影响了由Tat调控的两种重要的下游信号分子类型。miR-217导致的SIRT1表达降低增强了Tat诱导的IKK和p65-NFkB磷酸化，也加剧了Tat引发的AMPK磷酸化的丧失。我们的研究结果揭示了Tat与靶向SIRT1的特定宿主细胞miRNA之间以前未知的联系。我们还证明，这种调控机制影响p65-NFkB和AMPK信号传导：这两条影响HIV-1发病机制的重要宿主细胞途径。我们的研究结果还表明，通过下调miR-217来增加SIRT1蛋白表达的策略可能对预防HIV-1复制具有治疗益处。
