Not all transcribed eukaryotic RNAs are precisely protein-coding, some seem to be non-functional and are the results of spurious transcription, while many others play pivotal roles in specific regulation of gene expression and direct translation. The regulation in the shape of gene silencing occurs at two stages of transcriptional and post-transcriptional. In transcriptional layer, either an RNA-directed DNA methylation and/or chromatin remodeling can be modulated by non-protein coding RNAs in the nucleus. In post-transcriptional regulation, sequence-specific regulation of complementary target mRNAs is remaining the principal cause. miRNA-mediated gene regulation machinery that triggers the regular transcription of mRNAs is evolutionarily ancient and is the topic of this review.

并非所有转录的真核RNA都是精确的蛋白质编码，有些似乎是无功能的，是伪转录的结果，而许多其他的真核RNA在基因表达和直接翻译的特定调节中起着关键作用。基因沉默形状的调节发生在转录和转录后两个阶段。在转录层中，RNA定向的DNA甲基化和/或染色质重塑可以通过细胞核中非蛋白质编码的RNA进行调节。在转录后调控中，互补靶mRNA的序列特异性调控仍是主要原因。触发mRNA正常转录的miRNA介导的基因调控机制在进化上是古老的，并且是本综述的主题。