Summary
MicroRNAs (miRNAs) are considered as key regulators of literally all cellular pathways.
Therefore, miRNA biosynthesis and their individual cellular functions must be tightly
regulated as well. MiRNAs are transcribed as primary transcripts, which are processed
to mature miRNAs in two consecutive maturation steps. Finally, the mature miRNA is
incorporated into a miRNA-protein complex, where it directly interacts with a member
of the Argonaute (Ago) protein family. The miRNA guides such protein complexes to
partial complementary target sites, which are typically located in the 3’ untranslated
region (UTR) of mRNAs leading to inhibition of gene expression. MiRNA activity and
abundance is regulated on various levels ranging from transcription and processing
to target site binding and miRNA stability. Recent advances in our understanding of
how miRNA activity is regulated in mammalian cells are summarised and discussed in
this review article.
Keywords
microRNAs - Dicer - Drosha - Argonaute - gene silencing