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Argonaute 2/RISC resides in sites of mammalian mRNA decay known as cytoplasmic bodies


RNA interference (RNAi) is an important means of eliminating mRNAs, but the intracellular location of RNA-induced silencing complex (RISC) remains unknown. We show here that Argonaute 2, a key component of RISC, is not randomly distributed but concentrates in mRNA decay centres that are known as cytoplasmic bodies. The localization of Argonaute 2 in decay centres is not altered by the presence or absence of small interfering RNAs or their targeted mRNAs. However, RNA is required for the integrity of cytoplasmic bodies because RNase eliminates Argonaute 2 localization. In addition, Argonaute 1, another Argonaute family member, is concentrated in cytoplasmic bodies. These results provide new insight into the mechanism of RNAi function.

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Figure 1: Localization of Ago2 in discrete foci within human cells.
Figure 2: Ago2 colocalizes and associates with Ago1.
Figure 3: Ago2 resides in sites of mRNA decay.
Figure 4: Ago2 localizes to cytoplasmic bodies in the presence of shRNA with its targeted mRNA, and requires RNA for mRNA decay centre localization.

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We thank T. Tuschl for the Flag-tagged Ago1 and Ago2 constructs, J. Lykke-Andersen for the Flag-tagged Dcp1a and Dcp2 constructs, and R. Wolkowicz for HEK 293 cells stably expressing the ecotropic receptor. We thank T. Wehrman for discussions and help with experiment design. This work was supported by a graduate fellowship from the Howard Hughes Medical Institute to G.L.S., and NIH grants AG09521, AG20961, HL65572 and HD18179, Ellison Medical Foundation Grant AG-33-0817, and support from the Baxter Foundation to H.M.B.

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Correspondence to Helen M. Blau.

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Sen, G., Blau, H. Argonaute 2/RISC resides in sites of mammalian mRNA decay known as cytoplasmic bodies. Nat Cell Biol 7, 633–636 (2005).

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