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. Author manuscript; available in PMC: 2015 Aug 1.
Published in final edited form as: Epilepsia. 2014 Jun 25;55(8):1170–1186. doi: 10.1111/epi.12692

Figure 6. MicroRNA biogenesis and function.

Figure 6

miRNA genes are transcribed to generate primary miRNA (pri-miRNA) transcripts with a hairpin secondary structure. Pri-miRNAs are cleaved by a multiprotein complex that includes Drosha, generating pre-miRNAs that are exported into the cytoplasm by Exportin 5. In the cytoplasm, Dicer cleaves the hairpin loop, producing miRNA duplexes that are then unwound to yield single-strand mature miRNAs. Finally, mature miRNAs are incorporated into the RNA-induced silencing complex (RISC) in a sequence of events involving several proteins, including Argonaute proteins like Ago2. Once incorporated into RISC, miRNAs guide the complex to specific mRNAs through complementary base-pairing, leading to their cleavage or repression. Respective mechanisms appear to be active in epileptic brain tissue.