miRNA前体（pri-miRNA）在细胞核中经过两步剪切加工为成熟的miRNA，在细胞质中行使靶基因RNA的降解和翻译抑制作用。我们的研究发现，HYL1 除了定位在细胞核中参与 miRNA 加工外，还同时定位在细胞质中，当HYL1与细胞质定位信号融合后其转基因植株中miRNA靶基因mRNA的剪切能力没有改变，但是翻译抑制的能力明显增强。由此推测，HYL1参与miRNA靶基因转录产物的翻译抑制。为了揭示这一现象的分子机制，我们准备以模式植物拟南芥HYL1基因突变体为研究对象，研究HYL1与细胞质定位信号融合蛋白在细胞质中的表达水平，了解这些融合蛋白对miRNA靶基因mRNA剪切和翻译抑制过程的调控能力，分析HYL1蛋白二聚化对其亚细胞定位和翻译调控的影响，解析HYL1在核糖体内参与靶基因翻译抑制的的可能性及过程，提出HYL1在细胞质中调控靶基因翻译抑制的分子机制。

Primary transcripts (pri-miRNAs) are processed in the nucleus and release mature miRNAs into cytoplam after two steps of cleavage and control the gene silencing by cleavage and tranlation repression of miRNA-targeted genes. Our previous studies show that HYL1 is localized not only in nuclear but also in cytoplasm and that the fused proteins of HYL1 with cytoplam-localization signal (CLS) in the transgenic plants do not change the cleavage of miRNA-targeted genes but enhance plant ability of tranlation repression. The hypothesis is that HYL1 is involved in translational repression of miRNAs to their traget genes. To verify this hypothesis, we will use the loss-of-function mutants of HYL1 gene to study: the translational levels of HYL-CLS fused proteins; evaluate the ability of these proteins to regulate the cleavage and translation of the target genes; analyze the effects of HYL1 homodimerization on the cleavage and tranlation repression of miRNA-targeted genes; disclose the posibility and procedures for regulation of HYL1 to translational repression of miRNAs to their targete genes; and propose the molecular mechanism underlying the regulation of HYL1 to translational repression of miRNAs to their targete genes in cytoplasm.