Project description:RRF-3 and ERI-1 are first identified proteins required for accumulation of at least some endogenous secondary siRNAs in C.elegans. Genome wide gene expression analysis was performed on L4 stage rrf-3 and eri-1 mutant C. elegans to study effects caused by loss of these proteins. Mutant rrf-3 and eri-1 strains exhibited similar expression patterns when compared to N2 wild type, while 72 transcripts were found to be co-overexpressed and 4 transcripts co-underexpressed (> 2-fold, p< 0.05). Ontology analysis indicated many of the gene products were associated with protein phosphorylation and sperm function. These results provide additional support for the hypothesis that RRF-3 and ERI-1 act together in a siRNA pathway and may indicate biological processes that are related to endo-siRNAs. Experiment Overall Design: rrf-3(pk1426) mutant worms (NL2099), eri-1 (mg366) mutant worms (GR1373), and wild type worms (N2) were grown on culturing plates containing NGM agar media with OP50 Escherichia coli (E. coli). Worms were grown at 20°C and harvested at L4 stage. RNA isolation was made using Ribopure Total RNA isolation -kit (Ambion). Animals were grown and RNA isolated separately for each biological replicate. Total RNA was labeled for chip experiments using the cRNA protocol (Affymetrix, Palo Alto, CA). DNA from each mutant was hybridized to Gene Chip C. elegans whole genome arrays containing 22,500 transcripts (Affymetrix, Palo Alto, CA) as three biological replicates (3 chips each for N2, rrf-3, eri-1). Microarray hybridization and scanning was performed at the Biomedicum Biochip Center (Helsinki, Finland).
Project description:RRF-3 and ERI-1 are first identified proteins required for accumulation of at least some endogenous secondary siRNAs in C.elegans. Genome wide gene expression analysis was performed on L4 stage rrf-3 and eri-1 mutant C. elegans to study effects caused by loss of these proteins. Mutant rrf-3 and eri-1 strains exhibited similar expression patterns when compared to N2 wild type, while 72 transcripts were found to be co-overexpressed and 4 transcripts co-underexpressed (> 2-fold, p< 0.05). Ontology analysis indicated many of the gene products were associated with protein phosphorylation and sperm function. These results provide additional support for the hypothesis that RRF-3 and ERI-1 act together in a siRNA pathway and may indicate biological processes that are related to endo-siRNAs. Keywords: Mutant vs. wild type -comparison
Project description:Short interfering RNAs (siRNAs) are a class of regulatory effectors that enforce gene silencing though formation of RNA duplexes. While progress has been made in identifying the capabilities of siRNAs in silencing of foreign RNA and transposable elements, siRNA functions in endogenous gene regulation have remained mysterious. In certain organisms, siRNA biosynthesis involves novel enzymes that act as RNA-directed RNA polymerases (RdRPs). Here we analyze the function of a C. elegans RdRP, RRF-3, during spermatogenesis. We found that loss of RRF-3 function resulted in pleiotropic defects in sperm development, and that sperm defects led to embryonic lethality. Notably, sperm nuclei in mutants of either rrf-3 or another component of the siRNA pathway, eri-1, were frequently surrounded by ectopic microtubule structures, with spindle abnormalities in a subset of the resulting embryos. Through high-throughput small RNA sequencing, we identified a population of cellular mRNAs from spermatogenic cells that appear to serve as templates for antisense siRNA synthesis. This set of genes includes the majority of genes known to have enriched expression during spermatogenesis, as well as many genes not previously known to be expressed during spermatogenesis. For a subset of these genes, we found that RRF-3 was required for effective siRNA accumulation. These and other data suggest a working model in which a major role for the RRF-3/ERI pathway is to generate siRNAs that set patterns of gene expression through feedback repression of a set of critical targets during spermatogenesis Sequencing of small RNAs from a population of C. elegans isolated spermatogenic cells and from two paired sets of rrf-3 mutant and control whole males
Project description:Short interfering RNAs (siRNAs) are a class of regulatory effectors that enforce gene silencing though formation of RNA duplexes. While progress has been made in identifying the capabilities of siRNAs in silencing of foreign RNA and transposable elements, siRNA functions in endogenous gene regulation have remained mysterious. In certain organisms, siRNA biosynthesis involves novel enzymes that act as RNA-directed RNA polymerases (RdRPs). Here we analyze the function of a C. elegans RdRP, RRF-3, during spermatogenesis. We found that loss of RRF-3 function resulted in pleiotropic defects in sperm development, and that sperm defects led to embryonic lethality. Notably, sperm nuclei in mutants of either rrf-3 or another component of the siRNA pathway, eri-1, were frequently surrounded by ectopic microtubule structures, with spindle abnormalities in a subset of the resulting embryos. Through high-throughput small RNA sequencing, we identified a population of cellular mRNAs from spermatogenic cells that appear to serve as templates for antisense siRNA synthesis. This set of genes includes the majority of genes known to have enriched expression during spermatogenesis, as well as many genes not previously known to be expressed during spermatogenesis. For a subset of these genes, we found that RRF-3 was required for effective siRNA accumulation. These and other data suggest a working model in which a major role for the RRF-3/ERI pathway is to generate siRNAs that set patterns of gene expression through feedback repression of a set of critical targets during spermatogenesis
Project description:We analyzed the C. elegans small RNA response to high copy transgene sequences expressed in the soma in a wild type and an eri-6/7 mutant background. We also analyzed small RNA defects in the arl-8(tm2472) mutant. Transgene siRNAs are 22 nt long, mostly antisense, and correspond to the promoter, coding regions, the 3'UTR and plamsid sequences present on the transgene. Transgene siRNAs are decreased in the eri-6/7 mutant. In the arl-8 mutant, 26G siRNAs in the ALG-3/4 dependent endogenous RNAi pathway are decreased. Sequencing small RNAs from C. elegans transgenic strains and mutants.
Project description:The double-stranded RNA-binding protein Staufen has been implicated in various posttranscriptional gene regulatory processes. Here, we demonstrate that the Caenorhabditis elegans homolog of Staufen, STAU-1, functionally interacts with microRNAs. Loss-of-function mutations of stau-1 significantly suppress phenotypes of let-7 family microRNA mutants, a hypomorphic allele of dicer and a lsy-6 microRNA partial loss-of-function mutant. Furthermore, STAU-1 modulates the activity of lin-14, a target of lin-4 and let-7 family microRNAs, and this modulation is abolished when the 3' untranslated region of lin-14 is removed. Deep sequencing of small RNA cDNA libraries reveals no dramatic change in the levels of microRNAs, or other small RNA populations between wild-type and stau-1 mutants, with the exception of certain endogenous siRNAs in the WAGO pathway. The modulation of microRNA activity by STAU-1 does not seem to be associated with the previously reported enhanced exogenous RNAi (Eri) phenotype of stau-1 mutants, since eri-1 exhibits the opposite effect on microRNA activity. Altogether, our results suggest that STAU-1 negatively modulates microRNA activity downstream of biogenesis, possibly by competing with microRNAs for binding on the 3' untranslated region of target mRNAs
Project description:The double-stranded RNA-binding protein Staufen has been implicated in various posttranscriptional gene regulatory processes. Here, we demonstrate that the Caenorhabditis elegans homolog of Staufen, STAU-1, functionally interacts with microRNAs. Loss-of-function mutations of stau-1 significantly suppress phenotypes of let-7 family microRNA mutants, a hypomorphic allele of dicer and a lsy-6 microRNA partial loss-of-function mutant. Furthermore, STAU-1 modulates the activity of lin-14, a target of lin-4 and let-7 family microRNAs, and this modulation is abolished when the 3' untranslated region of lin-14 is removed. Deep sequencing of small RNA cDNA libraries reveals no dramatic change in the levels of microRNAs, or other small RNA populations between wild-type and stau-1 mutants, with the exception of certain endogenous siRNAs in the WAGO pathway. The modulation of microRNA activity by STAU-1 does not seem to be associated with the previously reported enhanced exogenous RNAi (Eri) phenotype of stau-1 mutants, since eri-1 exhibits the opposite effect on microRNA activity. Altogether, our results suggest that STAU-1 negatively modulates microRNA activity downstream of biogenesis, possibly by competing with microRNAs for binding on the 3' untranslated region of target mRNAs Deep-sequencing was performed on cDNA libraries made from total RNA from young adults populations of two strains: wild-type (N2) and stau-1(tm2266), in three biological replicates each strain.
Project description:To examine the roles of the ADAR genes and the ERI-6/7 helicase in endogenous RNAi pathways, we sequenced small RNA of adr-1; adr-2; eri-6 mutants. We also analyzed the transcriptomes of these mutants using total RNAseq and mRNAseq. mRNAseq was done in mutants depleted for the RNAi factors drh-1 and nrde-3, or control RNAi
Project description:Adenosine deaminases that act on RNA (ADARs) catalyze the conversion of adenosine to inosine in dsRNA. C. elegans ADARs, ADR-1 and ADR-2, promote the expression of genes containing dsRNA structures by preventing their processing into siRNAs and silencing by RNAi. The 26G endogenous siRNA (endo-siRNA) pathway generates a subset of siRNAs distinct from those made in adr-1;adr-2 mutants, but using many of the same factors. We found that adr-1;adr-2;rrf-3 mutants, lacking both ADARs and the RNA-dependent RNA polymerase RRF-3 required for the 26G pathway, display a bursting phenotype rescued by the RNAi factors RDE-1 and RDE-4. To determine what gene expression changes underlie the synthetic phenotype of adr-1;adr-2;rrf-3 mutants, we sequenced poly(A)+ RNA from adr-1;adr-2;rrf-3 embryos, their parent strains, and strains rescued with mutations in rde-1 and rde-4. We found that genes associated with edited structures were robustly downregulated in adr-1;adr-2;rrf-3 mutants in a manner partially dependent on rde-1 and rde-4. Additionally, genes induced during Orsay virus infections were induced in rrf-3 mutants and further upregulated in adr-1;adr-2;rrf-3 mutants, again dependent in part on rde-1 and rde-4.
Project description:We analyzed the C. elegans small RNA response to high copy transgene sequences expressed in the soma in a wild type and an eri-6/7 mutant background. We also analyzed small RNA defects in the arl-8(tm2472) mutant. Transgene siRNAs are 22 nt long, mostly antisense, and correspond to the promoter, coding regions, the 3'UTR and plamsid sequences present on the transgene. Transgene siRNAs are decreased in the eri-6/7 mutant. In the arl-8 mutant, 26G siRNAs in the ALG-3/4 dependent endogenous RNAi pathway are decreased.