What are miRNAs?
Mature microRNA (miRNA) are a class of small, single-stranded RNAs involved primarily in the negative regulation of gene expression.
Mechnism of miRNA Action
miRNAs interact with target mRNAs at specific sites to induce cleavage of the message or inhibit translation.
miRNAs act as adaptors that employ a silencing complex (RNA-induced silencing complex, RISC) to target mRNAs by selective base-apiring, primarly in the 3′-UTR (untranslated region). Target interaction does not require perfect complementarity between miRNA and mRNA sequences, although near-perfect base-pairing in a small region in the 5′ end (positions 2-8) of the micro RNA appears to be one of the key determinants of target recongnition. For further information on miRNA mechanisms please visit the page of Dr Martin Bushell.
Prediction of miRNA Targets
- Based on sequence complementarity to target sites with emphasis on perfect base-pairing in the 5′ end positions 2-8 of the microRNA. e.g. TargetScan, PicTar, TargetRank.
- Based on calculation of mRNA secondary structure and energetically favorable hybridization between microRNA and target mRNA. RNAhybrid, STarMir
- Experimentallty validated miRNA tareget (TarBase)
Stem cell and germline proliferation