Endomembrane-associated RSD-3 is important for RNAi induced by extracellular silencing RNA in both somatic and germ cells of Caenorhabditis elegans.
RNA silencing signals in C. elegans spread among cells, leading to RNAi throughout the body. During systemic spread of RNAi, membrane trafficking is thought to play important roles. Here, we show that RNAi Spreading Defective-3 (rsd-3), which encodes a homolog of epsinR, a conserved ENTH (epsin N-terminal homology) domain protein, generally participates in cellular uptake of silencing RNA. RSD-3 is previously thought to be involved in systemic RNAi only in germ cells, but we isolated several deletion alleles of rsd-3, and found that these mutants are defective in the spread of silencing RNA not only into germ cells but also into somatic cells. RSD-3 is ubiquitously expressed, and intracellularly localized to the trans-Golgi network (TGN) and endosomes. Tissue-specific rescue experiments indicate that RSD-3 is required for importing silencing RNA into cells rather than exporting from cells. Structure/function analysis showed that the ENTH domain alone is sufficient, and membrane association of the ENTH domain is required, for RSD-3 function in systemic RNAi. Our results suggest that endomembrane trafficking through the TGN and endosomes generally plays an important role in cellular uptake of silencing RNA.
Department of Physiology, Tokyo Women's Medical University School of Medicine, Tokyo, Japan.
Rieko
R
Imae
Department of Physiology, Tokyo Women's Medical University School of Medicine, Tokyo, Japan.
Katsufumi
K
Dejima
Department of Physiology, Tokyo Women's Medical University School of Medicine, Tokyo, Japan.
Eriko
E
Kage-Nakadai
Graduate School of Pharmaceutical Science, University of Tokyo, Tokyo, Japan.
Hiroyuki
H
Arai
Department of Physiology, Tokyo Women's Medical University School of Medicine, Tokyo, Japan.|Tokyo Women's Medical University Institute for Integrated Medical Sciences, Tokyo, Japan.
Shohei
S
Mitani
D033942:Adaptor Proteins, Vesicular Transport / Q000235:genetics*; D000818:Animals; D001692:Biological Transport / Q000235:genetics; D017173:Caenorhabditis elegans / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics*; D002450:Cell Communication / Q000235:genetics; D005854:Germ Cells / Q000378:metabolism; D000072417:Protein Domains / Q000235:genetics; D034622:RNA Interference / Q000502:physiology*; D034741:RNA, Small Interfering / Q000235:genetics*; D012097:Repressor Proteins / Q000235:genetics*; D019076:Transgenes / Q000235:genetics
D033942:Adaptor Proteins, Vesicular Transport; C525550:CTBP-1 protein, C elegans; D029742:Caenorhabditis elegans Proteins; D034741:RNA, Small Interfering; C000627114:RSD-3 protein, C elegans; D012097:Repressor Proteins; C114154:epsin