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. Author manuscript; available in PMC: 2017 Jul 1.
Published in final edited form as: J Hepatol. 2016 Mar 14;65(1):213–221. doi: 10.1016/j.jhep.2016.03.004

Figure 1. miRNA synthesis and contents of exosomes.

Figure 1

The pathway of miRNA synthesis and its function (top). In the nucleus, miRNAs are transcribed from DNA forming a primary transcript, pri-miRNA. The RNase III enzyme DROSHA cleaves pri-miRNA to produce a precursor, pre-miRNA that is transported to the cytoplasm through a nuclear export protein Exportin-5. In the cytoplasm, pre-miRNAs are cleaved by DICER to form a miRNA duplex. In general, only one strand of the miRNA duplex is used as the mature miRNA while the other strand is degraded because of less stability. Mature miRNA binds to the 3′UTR of target mRNA and is loaded into RNA-induced silencing complex (RISC). As a result, this complex inhibits the process of mRNA translation or enhances mRNA degradation leading to translational suppression.

Contents of exosomes (bottom). Typical exosomes contain various cargoes including pre-miRNAs, mature miRNAs, and mRNAs as well as membrane marker proteins, endosome-associated (MVB-derived) proteins, and heat shock proteins (chaperones).