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. Author manuscript; available in PMC: 2012 Oct 1.
Published in final edited form as: Epigenomics. 2011 Dec;3(6):747–759. doi: 10.2217/epi.11.97

Figure 1. MiRNA biogenesis and current status of miRNA research.

Figure 1

(A) miRNAs transcribed by RNA polymerase II into the primary miRNAs, having 5′ caps and poly-A tails. The primary miRNAs are processed by RNase III Drosha with its partner Pasha into the precursor miRNAs, which are then exported by the nuclear export factor Exporting 5 and its cofactor RAN-GTP into the cytoplasm. Once in the cytoplasm, the precursor miRNAs are further processed by another RNase III Dicer into the mature miRNAs. The mature miRNA is incorporated into the RISC complex and negatively regulates its target mRNA through two main mechanisms: when it binds to its target in a complementary manner, it leads to target mRNA cleavage and by binding to its target with incomplete complementary this leads to translational repression. (B) Approximate 10-year data collected from PubMed search engine under keywords ‘miRNA’ under defined limits.