Maciaszek J W, Talmage D A, Viglianti G A
Program in Molecular Medicine, University of Massachusetts Medical Center, Worcester 01605.
J Virol. 1994 Oct;68(10):6598-604. doi: 10.1128/JVI.68.10.6598-6604.1994.
The activation of human immunodeficiency virus type 1 (HIV-1) expression in latently infected cells by exogenous agents is believed to be important in the progression of AIDS. Most factors that are known to activate HIV-1 gene expression increase the binding of NF-kappa B or NF-kappa B-like transcription factors to the HIV-1 core enhancer region. In this report, we demonstrate that retinoic acid (RA) treatment of promonocytic U937 cells stimulates expression from the simian immunodeficiency virus (SIVmac) long terminal repeat (LTR). Furthermore, RA and phorbol 12-myristate 13-acetate (PMA) synergistically stimulated both SIVmac and HIV-1 LTRs to levels of expression comparable to that achieved by the viral transactivator Tat. The cis-acting elements required for a response to RA and PMA cotreatment are located between nucleotides -50 and +1 of SIVmac and between nucleotides -83 and +80 of HIV-1. Thus, the synergistic stimulation induced by RA and PMA is NF-kappa B independent. Analysis of deletion mutants of the SIVmac LTR demonstrates that RA and PMA stimulation cooperates with NF-kappa B and Sp1. An SIVmac LTR-reporter gene construct [pLTR(-50/+466)CAT] lacking NF-kappa B and Sp1 binding sites was not activated by Tat in untreated cells but was activated in cells that were cotreated with RA and PMA. Furthermore, gel retardation assays demonstrated that RA treatment causes a change in the pattern of a cellular factor(s) which binds to the -50 through +1 region of the SIVmac LTR. These data suggest that RA induces a PMA-activatable cellular factor that cooperates with NF-kappa B, Sp1, or Tat to stimulate LTR-directed transcription.
外源性因子激活潜伏感染细胞中1型人类免疫缺陷病毒（HIV-1）的表达被认为在艾滋病进展过程中至关重要。大多数已知可激活HIV-1基因表达的因子会增加核因子κB（NF-κB）或类NF-κB转录因子与HIV-1核心增强子区域的结合。在本报告中，我们证明用视黄酸（RA）处理单核细胞U937细胞可刺激猿猴免疫缺陷病毒（SIVmac）长末端重复序列（LTR）的表达。此外，RA和佛波酯12-肉豆蔻酸酯13-乙酸酯（PMA）协同刺激SIVmac和HIV-1的LTR，使其表达水平与病毒反式激活因子Tat所达到的水平相当。对RA和PMA联合处理产生反应所需的顺式作用元件位于SIVmac的核苷酸-50至+1之间以及HIV-1的核苷酸-83至+80之间。因此，RA和PMA诱导的协同刺激不依赖于NF-κB。对SIVmac LTR缺失突变体的分析表明，RA和PMA刺激与NF-κB和Sp1协同作用。缺乏NF-κB和Sp1结合位点的SIVmac LTR报告基因构建体[pLTR(-50/+466)CAT]在未处理的细胞中不被Tat激活，但在与RA和PMA联合处理的细胞中被激活。此外，凝胶阻滞试验表明，RA处理导致一种细胞因子与SIVmac LTR的-50至+1区域结合的模式发生变化。这些数据表明，RA诱导一种可被PMA激活的细胞因子，该因子与NF-κB、Sp1或Tat协同作用以刺激LTR指导的转录。
