中文摘要：

miRNA（microRNA）是一类广泛存在于高等真核细胞中的长度约为21个碱基的小分子非编码RNA,参与调控三分之一以上基因的表达,并与多种人类疾病存在重要关联。而siRNA（small interfering RNA）是RNA干扰（RNA interference,RNAi）中的效应分子,其结构和作用机制与miRNA存在许多类似之处。由于miRNA和siRNA具有重要的生物学功能。因此,对它们作用机制的理解具有非常重要的理论意义和应用指导价值。该综述将对它们作用机制的研究进展做一总结和回顾。

英文摘要：

Most of the eukaryotic organisms encode numerous small non-coding RNAs （ncRNAs）,which control the expression of thousands of genes and participate in almost every biology process. However,the mechanistic details of how these small oligonucleotides inhibit or stimulate their target gene production are still lacking. Recent studies have uncovered various mechanisms by which microRNA （miRNA） and small interfering RNA （siRNA） affect their target mRNA post-transcriptionally or transcriptionally. This review will focus on the current understanding of the regulatory mechanisms by miRNA and siRNA in animals.