Identification of functional microRNAs released through asymmetrical processing of HIV-1 TAR element
Identification of functional microRNAs released through asymmetrical processing of HIV-1 TAR element
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DOI：
10.1093/nar/gkn076
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发表时间：
2008-04-01
影响因子：
14.9
通讯作者：
Provost, Patrick
中科院分区：
文献类型：
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作者：
Ouellet, Dominique L.;Plante, Isabelle;Provost, Patrick
人类免疫缺陷病毒1型（HIV-1）和RNA沉默途径之间的相互作用是复杂和多方面的。对于有效的病毒转录和支持tat介导的病毒基因表达的反式激活至关重要，反式激活响应（TAR）元件是位于所有HIV-1转录本5端的结构化RNA。在这里，我们报道该元件是培养的hiv -1感染细胞系和hiv -1感染的人CD4+ T淋巴细胞中microRNAs （miRNAs）的来源。利用引物延伸和核糖核酸酶（RNase）保护试验，我们描绘了来自模型HIV-1转录物的TAR miRNA双链，即miR-TAR-5p和miR-TAR-3p。体外RNase分析表明，TAR底部缺乏游离3末端可能是其体内加工反应性低的原因。miR-TAR-5p和miR-TAR-3p都下调了TAR miRNA传感器的活性，这一过程需要一个完整的miRNA引导的RNA沉默机制。miR-TAR-3p表现出优越的基因下调作用，可能是由于其优先被RNase III Dicer从HIV-1 TAR RNA中释放。我们的研究表明，HIV-1转录本的TAR元件在Dicer的不对称加工过程中释放出功能性的miRNA，从而为病毒miRNA的生物发生提供了新的见解。
The interaction between human immunodeficiency virus type 1 (HIV-1) and RNA silencing pathways is complex and multifaceted. Essential for efficient viral transcription and supporting Tat-mediated transactivation of viral gene expression, the trans-activation responsive (TAR) element is a structured RNA located at the 5 end of all transcripts derived from HIV-1. Here, we report that this element is a source of microRNAs (miRNAs) in cultured HIV-1-infected cell lines and in HIV-1-infected human CD4+ T lymphocytes. Using primer extension and ribonuclease (RNase) protection assays, we delineated both strands of the TAR miRNA duplex deriving from a model HIV-1 transcript, namely miR-TAR-5p and miR-TAR-3p. In vitro RNase assays indicate that the lack of a free 3 extremity at the base of TAR may contribute to its low processing reactivity in vivo. Both miR-TAR-5p and miR-TAR-3p down-regulated TAR miRNA sensor activity in a process that required an integral miRNA-guided RNA silencing machinery. miR-TAR-3p exerted superior gene downregulatory effects, probably due to its preferential release from HIV-1 TAR RNA by the RNase III Dicer. Our study suggests that the TAR element of HIV-1 transcripts releases functionally competent miRNAs upon asymmetrical processing by Dicer, thereby providing novel insights into viral miRNA biogenesis.