A viral suppressor of RNA silencing differentially regulates the accumulation of short interfering RNAs and micro-RNAs in tobacco
A viral suppressor of RNA silencing differentially regulates the accumulation of short interfering RNAs and micro-RNAs in tobacco
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DOI：
10.1073/pnas.232434999
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发表时间：
2002-11-12
影响因子：
11.1
通讯作者：
Bowman, LH
中科院分区：
文献类型：
--
作者：
Mallory, AC;Reinhart, BJ;Bowman, LH
两大类小的非编码RNA已经成为真核生物中基因表达的重要调节因子，与RNA沉默相关的短干扰RNA（siRNA）和参与基因表达调节的内源性微小RNA（miRNA）。辅助组分蛋白酶（Helper component proteinase，HC-Pro）是一种能阻断植物RNA沉默的病毒蛋白。在这里，我们研究了HC-Pro对siRNA和内源性miRNA积累的影响。在响应于三种不同类型的转基因而沉默的转基因烟草植物中分析siRNA：有义转基因、反向重复转基因和扩增子转基因。HC-Pro抑制每个系中的沉默，阻断相关siRNA的积累并允许来自先前沉默的基因座的转录物的积累。HC-Pro-抑制在反向重复和扩增子转基因系中的沉默伴随着长双链RNA的明显积累和比沉默期间积累的siRNA大的小RNA的比例量。对这些结果的分析表明，HC-Pro通过抑制siRNA从双链RNA前体的加工或通过使siRNA不稳定来干扰沉默。与siRNA相反，内源性miRNA的积累在所有HC-Pro表达系中大大增强。因此，我们的研究结果表明，在植物中的siRNA和miRNA的积累可以通过病毒蛋白质的差异调节。HC-Pro影响miRNA途径的事实提高了植物病毒靶向该途径作为控制宿主中基因表达的手段的可能性。
Two major classes of small noncoding RNAs have emerged as important regulators of gene expression in eukaryotes, the short interfering RNAs (siRNAs) associated with RNA silencing and endogenous micro-RNAs (miRNAs) implicated in regulation of gene expression. Helper component-proteinase (HC-Pro) is a viral protein that blocks RNA silencing in plants. Here we examine the effect of HC-Pro on the accumulation of siRNAs and endogenous miRNAs. siRNAs were analyzed in transgenic tobacco plants silenced in response to three different classes of transgenes: sense-transgenes, inverted-repeat transgenes, and amplicon-transgenes. HC-Pro suppressed silencing in each line, blocking accumulation of the associated siRNAs and allowing accumulation of transcripts from the previously silenced loci. HC-Pro-suppression of silencing in the inverted-repeat- and amplicon-transgenic lines was accompanied by the apparent accumulation of long double-stranded RNAs and proportional amounts of small RNAs that are larger than the siRNAs that accumulate during silencing. Analysis of these results suggests that HC-Pro interferes with silencing either by inhibiting siRNA processing from double-stranded RNA precursors or by destabilizing siRNAs. In contrast to siRNAs, the accumulation of endogenous miRNAs was greatly enhanced in all of the HC-Pro-expressing lines. Thus, our results demonstrate that accumulation of siRNAs and miRNAs in plants can be differentially regulated by a viral protein. The fact that HC-Pro affects the miRNA pathway raises the possibility that this pathway is targeted by plant viruses as a means to control gene expression in the host.