The Vasa Homolog RDE-12 Engages Target mRNA and Multiple Argonaute Proteins to Promote RNAi in C. elegans

• Published in: Current biology Vol. 24; no. 8; pp. 845 - 851
• Main Authors: Shirayama, Masaki, Stanney, William, Gu, Weifeng, Seth, Meetu, Mello, Craig C.
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 14.04.2014
• Subjects: Amino Acid Sequence; Animals; Argonaute Proteins - metabolism; Blotting, Northern; Caenorhabditis elegans - physiology; Caenorhabditis elegans Proteins - genetics; Caenorhabditis elegans Proteins - metabolism; DEAD-box RNA Helicases - genetics; DEAD-box RNA Helicases - metabolism; Immunoblotting; Immunoprecipitation; Microscopy, Fluorescence; Molecular Sequence Data; RNA Interference - physiology; RNA, Messenger - metabolism; RNA-Binding Proteins - genetics; RNA-Binding Proteins - metabolism
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2014.03.008

Argonaute (AGO) proteins are key nuclease effectors of RNAi [1]. Although purified AGOs can mediate a single round of target RNA cleavage in vitro, accessory factors are required for small interfering RNA (siRNA) loading and to achieve multiple-target turnover [2, 3]. To identify AGO cofactors, we immunoprecipitated the C. elegans AGO WAGO-1, which engages amplified small RNAs during RNAi [4]. These studies identified a robust association between WAGO-1 and a conserved Vasa ATPase-related protein RDE-12. rde-12 mutants are deficient in RNAi, including viral suppression, and fail to produce amplified secondary siRNAs and certain endogenous siRNAs (endo-siRNAs). RDE-12 colocalizes with WAGO-1 in germline P granules and in cytoplasmic and perinuclear foci in somatic cells. These findings and our genetic studies suggest that RDE-12 is first recruited to target mRNA by upstream AGOs (RDE-1 and ERGO-1), where it promotes small RNA amplification and/or WAGO-1 loading. Downstream of these events, RDE-12 forms an RNase-resistant (target mRNA-independent) complex with WAGO-1 and may thus have additional functions in target mRNA surveillance and silencing. •Vasa ATPase-related protein RDE-12 promotes RNAi and virus suppression in C. elegans•RDE-12 is recruited to target mRNA by primary Ago RDE-1 in the RNAi pathway•RDE-12 promotes secondary siRNA biogenesis and associates with secondary Ago WAGO-1•RDE-12 localizes to P granules in germline and novel perinuclear foci in soma Shirayama et al. identify the Vasa homolog RDE-12 as a protein that promotes RNAi and virus suppression in C. elegans. RDE-12 is recruited to target mRNA by primary AGO RDE-1 to promote small RNA amplification. RDE-12 forms a complex with secondary AGO WAGO-1 in P granules and may have additional functions in target mRNA surveillance and silencing.