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Resources » Paper

Joseph D. Shih et al. (2007) International Worm Meeting "Double-stranded RNA uptake through the SID-1 channel is coupled to the RNA Induced Silencing Complex (RISC)."

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  • Comments on Joseph D. Shih et al. (2007) International Worm Meeting "Double-stranded RNA uptake through the SID-1 channel is coupled to the RNA Induced Silencing Complex (RISC)." (0)

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    Status:
    Publication type:
    Meeting_abstract
    WormBase ID:
    WBPaper00029920

    Joseph D. Shih, Michael C. Fitzgerald, Marie Sutherlin, & Craig P. Hunter (2007). Double-stranded RNA uptake through the SID-1 channel is coupled to the RNA Induced Silencing Complex (RISC) presented in International Worm Meeting. Unpublished information; cite only with author permission.

    In sid-1 mutant worms systemic RNAi is totally disabled although cell autonomous RNAi is fully functional.(1) SID-1 is a broadly expressed dsRNA channel protein enriched at the cell surface. To investigate SID-1 substrate specificity and transport properties, a heterologous assay system was developed using Drosophila S2 cells expressing SID-1.(2) SID-1 dependent uptake of long dsRNA in Drosophila S2 cells is rapid and ATP independent. Thus, SID-1 is a putative channel protein that enables systemic RNA interference (RNAi) in C. elegans by allowing import of RNAi silencing triggers and enables passive uptake of double-stranded RNA (dsRNA) when expressed in Drosophila S2 cells. We previously showed that SID-1 is required for the import or uptake of silencing information triggered by feeding RNAi into body wall muscle cells.(1) To directly evaluate the role of SID-1 in the transport of dsRNA between adjacent cells, we injected dsRNA into single C. elegans intestinal cells and then assessed RNAi silencing in both the injected cell and adjacent cells. Our single cell injections on a sid-1 genetic mosaic strain show that cell-to-cell spread of RNAi between adjacent intestinal cells requires SID-1 dependent export and import of dsRNA. Since SID-1 can transport dsRNA bidirectionally, we investigated whether dsRNA must be actively retained within the cell for efficient net transport. Proteins that comprise the RNA induced silencing complex (RISC) are obvious candidates for involvement in dsRNA retention. We therefore assayed for radiolabelled dsRNA retention in Drosophila S2 cells expressing SID-1 following RNAi knockdown of select RISC components. We show that retention of SID-1 transported dsRNA requires two early acting components of the RNA induced silencing complex (RISC): Dicer2 and Argonaute2. These results link systemic RNAi with the RNAi silencing machinery and suggest that transport of dsRNA by SID-1 is coupled to RISC assembly. (1) Winston et al., Science 2002, 295(5564):2456-2459. (2) Feinburg EH, Hunter CP, Science 2003, 301(5639):1545-1547.


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