MicroRNAs (miRNAs) are a recently discovered family of endogenous, non-coding RNA molecules approximately 22 nt in length . They negatively modulate gene expression post-transcriptionally by binding to the complementary sequence in the 3′ untranslated region of target messenger RNAs (mRNAs) . miRNAs are transcribed from genomic DNA by RNA polymerase II but not further translated into protein (non-coding RNA). Eventually, they are processed from primary transcripts known as pri-miRNAs to short stem-loop structures called pre-miRNA and finally to become functionally mature miRNA. Mature miRNA molecules are partially complimentary to target mRNA where they either repress translation or direct destructive cleavage . The first miRNA was described in 1993 by Lee and colleagues, who found miRNA-lin-4 is essential for the normal temporal control of diverse post-embryonic development in Caenorhabditis elegans by negatively regulating the level of LIN-14 protein via antisense RNA-RNA interaction . miRNAs have a large-scale effect as a new layer of gene regulation mechanism. It has been estimated that the vertebrate genome encodes up to 1000 unique miRNAs, which can regulate expression of at least 30% of genes [4,5].
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)