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. Author manuscript; available in PMC: 2009 Apr 1.
Published in final edited form as: Curr Opin Genet Dev. 2008 Mar 11;18(2):197–203. doi: 10.1016/j.gde.2008.01.008

Figure 2.

Figure 2

Roles of P-bodies (processing bodies) in miRNA and siRNA functions and post-transcriptional regulation in animals. Pol II transcription gives rise to imperfectly base-paired double-stranded pri-miRNAs as well as pre-mRNAs, both of which undergo processing in the nucleus followed by export to the cytoplasm. Pre-miRNAs processed by Drosha in the nucleus undergo further cleavage by Dicer in the cytoplasm and one strand is loaded into an Argonaute-containing RNA-induced silencing complex (RISC; denoted miRISC in the figure). Similarly, perfectly base-paired double-stranded siRNA precursors are diced and one strand is loaded into a RISC complex (denoted siRISC). The miRNA or siRNA strands within the RISC complexes target homologous mRNAs for translational arrest or destruction in P-bodies (GW bodies) that are enriched for activities including the AGO-interacting GW182 protein, decapping (DCP) and exonuclease (XRN1) enzymes and proteins of the nonsense-mediated decay (NMD) pathway. mRNAs targeted to P-bodies can also be stored and released to the cytoplasm for translation.