摘要
MicroRNAs(miRNAs)are small noncoding RNAs that are not translated into functional proteins.miRNAs were first discovered in Caenorhabditis elegans in 19931 but did not attract attention until 2000,when the first mammalian miRNA was discovered.2 The precursor of miRNAs is~70-100 nt,which forms a standard stem structure and becomes a 19-22-nt single stranded RNA after processing.miRNAs can bind to messenger RNAs(mRNAs)and silence gene expression by degrading target mRNAs.