Project description:To explore how ZSP-1 (and therefore Z granules) might contribute to germline RNAi, we asked if zsp-1(-) animals were able to produce 22G siRNAs in response to dsRNA exposure. We exposed wild-type and zsp-1(-) animals to dsRNA targeting the germline-expressed gene oma-1 and sequenced the resultant oma-1 22G siRNAs. We identified similar numbers of oma-1 siRNAs anti-sense to oma-1 after oma-1 RNAi on wild-type or zsp-1(-) animals. We also used this dataset to identify genes with differential level of targeted 22G siRNAs level in zsp-1(-) versus WT animals.
Project description:The goal of small RNA-seq is to identify the differentially expressed small RNAs (microRNA, 22G RNA, piRNA, snoRNA) in the wild-type (WT) and hrde-1 mutant of C.elegans at the normoxia reared and hypoxia treatment conditions at P0 generation, and those small RNAs maintained dysregulation in F1, F2 and F3 generation.
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:In the Caenorhabditis elegans germline, thousands of mRNAs are concomitantly expressed with antisense 22G-RNAs, which are loaded into the Argonaute CSR-1. Despite their essential functions for animal fertility and embryonic development, how CSR-1 22G-RNAs are produced remains unknown. Here, we show that CSR-1 slicer activity is primarily involved in triggering the synthesis of small RNAs on the coding sequences of germline mRNAs and post-transcriptionally regulates a fraction of targets. CSR-1-cleaved mRNAs prime the RNA-dependent RNA polymerase, EGO-1, to synthesize 22G-RNAs in phase with ribosome translation in the cytoplasm, in contrast to other 22G-RNAs mostly synthesized in germ granules. Moreover, codon optimality and efficient translation antagonize CSR-1 slicing and 22G-RNAs biogenesis. We propose that codon usage differences encoded into mRNA sequences might be a conserved strategy in eukaryotes to regulate small RNA biogenesis and Argonaute targeting
Project description:Small RNAs, including piRNAs, miRNAs and endogenous siRNAs, bind Argonaute proteins to form RNA-silencing complexes that target coding genes, transposons and aberrant RNAs. To assess the requirements for endogenous siRNA formation and activity in C. elegans, we developed a GFP-based sensor for the endogenous siRNA 22G siR-1, one of a set of abundant siRNAs processed from a precursor RNA mapping to the X chromosome, the X-cluster. Silencing of the sensor is also dependent on the partially complementary, unlinked 26G siR-O7 siRNA. We show that 26G siR-O7 acts in trans to initiate 22G siRNA formation from the X-cluster. The presence of several mispairs between 26G siR-O7 and the X-cluster mRNA, as well as mutagenesis of the siRNA sensor, indicates that siRNA target recognition is permissive to a degree of mispairing. From a candidate reverse genetic screen, we identified several factors required for 22G siR-1 activity, including the Argonaute ergo-1 and the 3' methyltransferase henn-1. Quantitative RT-PCR of small RNAs in a henn-1 mutant and deep sequencing of methylated small RNAs indicate that siRNAs and piRNAs that associate with PIWI clade Argonautes are methylated by HENN-1, while siRNAs and miRNAs that associate with non-PIWI clade Argonautes are not. Thus, PIWI-class Argonaute proteins are specifically adapted to associate with methylated small RNAs in C. elegans. This SuperSeries is composed of the following subset Series: GSE34320: Analysis of 22G siRNA triggered siRNA amplification in Caenorhabditis elegans GSE34321: Analysis of 3' 2'-O-methylated small RNAs in Caenorhabditis elegans Refer to individual Series
Project description:Small endogenous C. elegans RNAs from L4 and young adult worms were prepared for sequencing using a protocol derived from Batista et al., (2008) and Lau et al. (2001). The small-RNA libraries were constructed using a method that does not require a 5M-bM-^@M-^Y monophosphate (called 5M-bM-^@M-^Y monophosphate-independent method, Ambros et al., 2003) to profile secondary siRNAs that have 5M-bM-^@M-^Y triphosphorylated G. All preprocessed small-RNA reads were mapped to genome (ce6), allowing no mismatches. After excluding miRNAs, 21U RNAs, rRNAs, and other structural ncRNAs, the remaining reads were classified as 22G RNAs, 26G RNAs, and other siRNAs, based on their length and 5M-bM-^@M-2 terminal nucleotide. Small-RNA libraries were sequenced in L4 and young adult stages in C.elegans.
Project description:MicroRNAs (miRNA), discovered in C. elegans, are short non-coding RNAs that bind and regulate the expression of target mRNAs in animals and plants. C. elegans miRNAs bind to partially complementary sequences in the 3' UTR of the target mRNA, which results in translational repression through mRNA destabilization. The high-throughput sequencing of RNA cleavage fragments was performed to directly detect cleaved miRNA targets in C. elegans. Based on this analysis, miR-249 was identified as a potential miRNA that regulates a ZK637.6 pseudogene, paralogous to asna-1 (ZK637.5), by a cleavage mechanism with extensive, evolutionary conserved complementarity. Additionally, we validated miR-249-directed cleavage of the ZK637.6 by a gene-specific 5M-bM-^@M-^Y rapid amplification of cDNA ends and observed notable difference in expression of ZK637.6 in wild-type versus mir-249 mutant C. elegans. Furthermore, phosphate-independent small-RNA sequencing analysis revealed that miR-249 target genes, including ZK637.6 pseudogene, showed 22G-RNA productions dependent on miR-249 targeting. These findings may lead to a better understanding of the biological roles of miRNAs for pseudogenes in C. elegans. Total small RNAs from wild-type and mir-249 mutant in adult stage worms were subjected to small RNA sequencing using an Illumina platform with Tobacco Acid Pyrophosphatase (TAP) treatment, allowing detection of secondary siRNAs carrying 5M-bM-^@M-^Y-tri-phosphate.
Project description:Small endogenous C. elegans RNAs from L4 and young adult worms were prepared for sequencing using a protocol derived from Batista et al., (2008) and Lau et al. (2001). The small-RNA libraries were constructed using a method that does not require a 5’ monophosphate (called 5’ monophosphate-independent method, Ambros et al., 2003) to profile secondary siRNAs that have 5’ triphosphorylated G. All preprocessed small-RNA reads were mapped to genome (ce6), allowing no mismatches. After excluding miRNAs, 21U RNAs, rRNAs, and other structural ncRNAs, the remaining reads were classified as 22G RNAs, 26G RNAs, and other siRNAs, based on their length and 5′ terminal nucleotide.
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:Small RNA pathways defend the germlines of animals against selfish genetic elements and help to maintain genomic integrity. At the same time, their activity needs to be well-controlled to prevent silencing of ‘self’ genes. Here, we reveal a proteolytic mechanism that controls endogenous small interfering (22G) RNA activity in the Caenorhabditis elegans germline to protect genome integrity and maintain fertility. We find that WAGO-1 and WAGO-3 Argonaute proteins are produced as pro-proteins that are matured through proteolytic processing of their unusually proline-rich N-termini. In the absence of DPF-3, a P-granule-localized N-terminal dipeptidase orthologous to mammalian DPP8/9, processing fails, causing a change of identity of 22G RNAs bound to these WAGO proteins. Accumulation of repeat- and transposon-derived transcripts, DNA damage and sterility ensue. We propose that DPF-3 acts as a licensing factor for 22G RNA activity.