Metazoan miRNA and siRNA pathways. Representation of standard metazoan models for canonical miRNA biogenesis, mirtron biogenesis, and siRNA processing. The Drosha/Pasha protein complex is specific to canonical miRNA biogenesis and initiates cleavage of the primary miRNA (pri-miRNA) from transcribed mRNAs. Intronic miRNAs (mirtrons) bypass cleavage by Drosha/Pasha, generating precursor miRNAs (pre-miRNAs) via intron splicing of mRNAs. The Dicer and Argonaute proteins are responsible for further processing and transport of miRNAs, in addition to short-interfering RNAs (siRNAs) from exogenous sources, resulting in repression of mRNA targets.
Maxwell et al. BMC Genomics 2012 13:714 doi:10.1186/1471-2164-13-714