How does microRNA work?

MiRNAs typically bind to the 3' untranslated region (UTR) of target mRNAs. During mRNA degradation, the binding of the miRNA to the target mRNA leads to its degradation by cellular enzymes. The target mRNA is cleaved and degraded, preventing translation into protein. In contrast, during miRNA inhibition the binding of the miRNA to the mRNA prevents ribosomes from effectively translating the mRNA into protein, leading to translational repression. Ultimately, the result of miRNA binding to its target mRNA is the silencing of gene expression.