Project description:Diverse naturally-occurring small RNA species interact with Argonaute proteins to mediate sequence-specific regulation in animals. In addition to micro-RNAs (miRNAs), which collectively regulate thousands of target mRNAs, other endogenous small RNA species include the Piwi-associated piRNAs that are important for fertility and a less well-characterized class of small RNAs often referred to simply as endo-siRNAs. Here we have utilized deep-sequencing technology and C. elegans genetics to explore the biogenesis and function of endo-siRNAs. We describe conditional alleles of the dicer-related helicase, drh-3, that implicate DRH-3 in both the response to foreign dsRNA as well as the RNA-dependent RNA Polymerase (RdRP)-dependent biogenesis of a diverse class of endogenous small RNAs, termed 22G-RNAs. We show that 22G-RNAs are abundantly expressed in the germline and maternally inherited and are the products of at least two distinct 22G-RNA systems. One system is dependent on worm-specific AGOs, including WAGO-1, which localizes to germline nuage-related structures termed P-granules. The WAGO 22G-RNA system silences transposons, pseudogenes and cryptic loci as well as a number of genes. Finally, we demonstrate that components of the nonsense-mediated decay pathway function in at least one of the multiple, distinct WAGO surveillance pathways. These findings broaden our understanding of the biogenesis and diversity of 22G-RNA species and suggest potential novel regulatory functions for these small RNAs. 18 samples examined. Small RNA libraries generated from: C. elegans animals with mutations in the WAGO pathway and a WAGO-1 immunopercipitate.
Project description:To explore the roles of piRNAs and WAGO-class 22G-RNAs in regulating gene expression and transposon silencing in Caenorhabditis elegans, we used RNA-seq to assess changes in small RNA and mRNA levels in prg-1 and mut-16 mutants, which disable the piRNA and WAGO-class 22G-RNA pathways respectively. We identified numerous roles for piRNAs and WAGO-class 22G-RNAs in regulating germline genes, including transposons, histones, and spermatogenic and oogenic transcripts.
Project description:Diverse naturally-occurring small RNA species interact with Argonaute proteins to mediate sequence-specific regulation in animals. In addition to micro-RNAs (miRNAs), which collectively regulate thousands of target mRNAs, other endogenous small RNA species include the Piwi-associated piRNAs that are important for fertility and a less well-characterized class of small RNAs often referred to simply as endo-siRNAs. Here we have utilized deep-sequencing technology and C. elegans genetics to explore the biogenesis and function of endo-siRNAs. We describe conditional alleles of the dicer-related helicase, drh-3, that implicate DRH-3 in both the response to foreign dsRNA as well as the RNA-dependent RNA Polymerase (RdRP)-dependent biogenesis of a diverse class of endogenous small RNAs, termed 22G-RNAs. We show that 22G-RNAs are abundantly expressed in the germline and maternally inherited and are the products of at least two distinct 22G-RNA systems. One system is dependent on worm-specific AGOs, including WAGO-1, which localizes to germline nuage-related structures termed P-granules. The WAGO 22G-RNA system silences transposons, pseudogenes and cryptic loci as well as a number of genes. Finally, we demonstrate that components of the nonsense-mediated decay pathway function in at least one of the multiple, distinct WAGO surveillance pathways. These findings broaden our understanding of the biogenesis and diversity of 22G-RNA species and suggest potential novel regulatory functions for these small RNAs.
Project description:Argonaute proteins (AGOs) are key nuclease effectors of RNA interference (RNAi) [1]. Although purified AGOs can mediate a single round of target-RNA cleavage in vitro, accessory factors are required for siRNA loading and to achieve multiple-target turnover [2, 3]. To identify AGO co-factors 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 co-localizes with WAGO-1 in germline P-granules and to peri-nuclear cytoplasmic foci in somatic cells. These findings and our genetic studies suggest that (i) RDE-12 is first recruited to target mRNAs by upstream AGOs (RDE-1 and ERGO-1) where it promotes small-RNA amplification and/or WAGO-1 loading, and that (ii) downstream of these events, RDE-12 forms an RNase-resistant (target mRNA-independent) complex with WAGO-1 that may scan for additional target mRNAs. Examine small RNA population changes in rde-12 mutants
Project description:Germ granules are liquid-like condensates that regulate small RNA pathways and gene expression, ensuring genome stability and fertility in animals. In C. elegans, several Argonaute proteins, central players of small RNA pathways, localize to germ granules, yet the functional significance of this spatial enrichment remains unclear. Here, we disrupted the localization of WAGO-4 to germ granules by introducing targeted mutations in the FG repeats of Vasa-like GLH proteins. These mutations did not disrupt overall germ granule architecture but significantly reduced WAGO-4 partitioning, leading to its predominant localization in the cytoplasm. Functional analyses revealed that this mislocalization partially compromised WAGO-4 activity, resulting in reduced WAGO-4 binding of small RNAs targeting specific genes, particularly those not co-regulated by CSR-1. This selective effect highlights the importance of WAGO-4’s spatial localization for efficient small RNA loading and gene regulation. Our findings demonstrate that germ granules serve as specialized compartments that fine-tune Argonaute function, emphasizing the role of phase-separated condensates in modulating RNA pathways and gene regulatory networks.
Project description:Germ granules are liquid-like condensates that regulate small RNA pathways and gene expression, ensuring genome stability and fertility in animals. In C. elegans, several Argonaute proteins, central players of small RNA pathways, localize to germ granules, yet the functional significance of this spatial enrichment remains unclear. Here, we disrupted the localization of WAGO-4 to germ granules by introducing targeted mutations in the FG repeats of Vasa-like GLH proteins. These mutations did not disrupt overall germ granule architecture but significantly reduced WAGO-4 partitioning, leading to its predominant localization in the cytoplasm. Functional analyses revealed that this mislocalization partially compromised WAGO-4 activity, resulting in reduced WAGO-4 binding of small RNAs targeting specific genes, particularly those not co-regulated by CSR-1. This selective effect highlights the importance of WAGO-4’s spatial localization for efficient small RNA loading and gene regulation. Our findings demonstrate that germ granules serve as specialized compartments that fine-tune Argonaute function, emphasizing the role of phase-separated condensates in modulating RNA pathways and gene regulatory networks.
Project description:There were several MS experiments used in this study: 1) Proximity labeling of the P granules 2) Protein levels estimation from whole worm lysates and 3) wago-4 KO expression check (PRM analysis). 1) Proximity labeling strategy was used to estimate P granule composition in 3xFG mutant (FG domains of GLH-1, GLH-2, and GLH-4 mutated) and compare it to the WT. PGL-3 was tagged with TurboID at its native locus using CRISPR-Cas9. Biotinylation level was determined after streptavidin pull-down followed by MS analysis, serving as a proxy for protein enrichment in P granules. 2) Whole-worm lysate MS analysis was performed on 3xFG mutant worms to assess the worm proteome at an elevated temperature (26 °C), where these mutants exhibit a fecundity phenotype. 3) A STOP codon was introduced in the second exon of the WAGO-4 gene at its native locus in C. elegans (WAGO-4 KO). To assess whether the WAGO-4 protein is expressed in this strain, lysates from WAGO-4 KO (in triplicate) and N2 (WT control) were analyzed using PRM-MS.