The action of ARGONAUTE1 in the miRNA pathway and its regulation by the miRNA pathway are crucial for plant development
The action of ARGONAUTE1 in the miRNA pathway and its regulation by the miRNA pathway are crucial for plant development
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DOI：
10.1101/gad.1201404
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发表时间：
2004-05-15
影响因子：
10.5
通讯作者：
Bartel, DP
中科院分区：
文献类型：
--
作者：
Vaucheret, H;Vazquez, F;Bartel, DP
MicroRNAs(MiRNAs)是一种内源性的21-24-NT RNA，通过与蛋白质编码基因的信息配对来下调基因的表达，从而指定mRNA的切割或抑制生产性翻译。它们在RNA诱导沉默复合体(RISC)内发挥作用，在动物中，RISC包含ArgAerte蛋白质家族的一个成员。在本研究中，我们表明拟南芥ago1突变体增加了已知被miRNAs切割的mRNAs的积累。在亚型ago1等位基因中，这种受损的miRNA功能发生在miRNA积累没有实质性变化的情况下，而在空等位基因中，它伴随着一些miRNAs的下降。因此，Ago1在拟南芥miRNA途径中发挥作用，可能在miRNA编程的RISC中发挥作用，因此Ago1的缺失会破坏一些miRNAs的稳定。我们还表明，MIR168靶向Ago1 mRNA是植物正常发育所必需的，说明了通过这种miRNA进行反馈控制的重要性。表达与MIR168互补性降低的突变体Ago1mRNA的转基因植株过量积累Ago1mRNA，并表现出与dcl1、hen1和hyl1突变体部分重叠的发育缺陷，表现出miRNA积累减少。MiRNA靶标在抗MIR168的植物中过度积累，这表明大量过剩的Ago1蛋白干扰了RISC或隔离miRNAs或其他RISC组分的功能。由MIR168抗性的Ago1mRNA引起的发育缺陷可以通过与突变体Ago1mRNA互补的补偿性miRNA来修复，证明了MIR168与其靶标之间的调控关系，并为在植物中设计人工miRNAs开辟了道路。
MicroRNAs (miRNAs) are endogenous 21-24-nt RNAs that can down-regulate gene expression by pairing to the messages of protein-coding genes to specify mRNA cleavage or repression of productive translation. They act within the RNA-induced silencing complex (RISC), which in animals contains a member of the Argonaute family of proteins. In the present study, we show that Arabidopsis ago1 mutants have increased accumulation of mRNAs known to be targeted for cleavage by miRNAs. In hypomorphic ago1 alleles, this compromised miRNA function occurs without a substantial change in miRNA accumulation, whereas in null alleles it is accompanied by a drop in some of the miRNAs. Therefore, AGO1 acts within the Arabidopsis miRNA pathway, probably within the miRNA-programmed RISC, such that the absence of AGO1 destabilizes some of the miRNAs. We also show that targeting of AGO1 mRNA by miR168 is needed for proper plant development, illustrating the importance of feedback control by this miRNA. Transgenic plants expressing a mutant AGO1 mRNA with decreased complementarity to miR168 overaccumulate AGO1 mRNA and exhibit developmental defects partially overlapping with those of dcl1, hen1, and hyl1 mutants showing a decrease in miRNA accumulation. miRNA targets overaccumulate in miR168-resistant plants, suggesting that a large excess of AGO1 protein interferes with the function of RISC or sequesters miRNAs or other RISC components. Developmental defects induced by a miR168-resistant AGO1 mRNA can be rescued by a compensatory miRNA that is complementary to the mutant AGO1 mRNA, proving the regulatory relationship between miR168 and its target and opening the way for engineering artificial miRNAs in plants.