microRNAs: Tiny silencers of gene expression

MicroRNAs are genome-encoded, around 22 nucleotide-long RNAs that silence gene expression post-transcriptionally by binding 3′ untranslated regions of messenger RNAs. Although recent years amassed a wealth of information about their biogenesis and biological functions, the mechanisms allowing miRNAs to silence gene expression is not fully understood. Our long-term goal is to understand in molecular terms how miRNAs repress hundreds of mRNA targets in animal cells.