Defective RNA processing enhances RNA silencing and influences flowering of Arabidopsis
Defective RNA processing enhances RNA silencing and influences flowering of Arabidopsis
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DOI：
10.1073/pnas.0606536103
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发表时间：
2006-10-10
影响因子：
11.1
通讯作者：
Baulcombe, David C.
中科院分区：
文献类型：
--
作者：
Herr, Alan J.;Molnar, Attila;Baulcombe, David C.
许多真核细胞使用RNA介导的沉默机制来保护免受病毒和转座子的攻击，并在转录后水平抑制内源基因表达。RNA沉默还涉及影响染色体结构和转录基因沉默的表观遗传机制。在这里，我们描述了增强沉默表型（esp）突变体在拟南芥，揭示了如何与RNA加工和3'端形成蛋白质可以影响RNA沉默。这些蛋白质是酵母PRP 2 RNA剪接辅因子的推定DEAH RNA解旋酶同源物和mRNA 3'末端形成蛋白CstF 64、symplekin/PTA 1和CPSF 100的同源物。最后两种蛋白质与3'端形成复合物AtCPSF中的开花时间调节因子FY物理相关。Tend形成esp突变体的表型包括转基因转录物的终止受损、早花和FCA-β mRNA的沉默增强。基于这些发现，我们提出含ESP的3'末端形成复合物阻止转基因和内源性mRNA进入RNA沉默途径。根据该提议，在不存在这些ESP蛋白的情况下，这些RNA具有异常的3'末端。这些异常的RNA会进入RNA沉默途径，因为它们被RNA依赖性RNA聚合酶转化为dsRNA。
Many eukaryotic cells use RNA-directed silencing mechanisms to protect against viruses and transposons and to suppress endogenous gene expression at the posttranscriptional level. RNA silencing also is implicated in epigenetic mechanisms affecting chromosome structure and transcriptional gene silencing. Here, we describe enhanced silencing phenotype (esp) mutants in Arabidopsis thaliana that reveal how proteins associated with RNA processing and 3' end formation can influence RNA silencing. These proteins were a putative DEAH RNA helicase homologue of the yeast PRP2 RNA splicing cofactor and homologues of mRNA 3' end formation proteins CstF64, symplekin/PTA1, and CPSF100. The last two proteins physically associated with the flowering time regulator FY in the 3' end formation complex AtCPSF. The phenotypes of the Tend formation esp mutants include impaired termination of the transgene transcripts, early flowering, and enhanced silencing of the FCA-beta mRNA. Based on these findings, we propose that the ESP-containing 3' end formation complexes prevent transgene and endogenous mRNAs from entering RNA-silencing pathways. According to this proposal, in the absence of these ESP proteins, these RNAs have aberrant 3' termini. The aberrant RNAs would enter the RNA silencing pathways because they are converted into dsRNA by RNA-dependent RNA polymerases.