Comparative analysis of piRNA sequences, targets and functions in Caenorhabditis nematodes
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ABSTRACT:
PROVIDER: PRJNA839379 | ENA |
REPOSITORIES: ENA
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Project description:Piwi proteins and Piwi-interacting RNAs (piRNAs) are best known for their roles in suppressing transposons and promoting fertility. Yet piRNA biogenesis and its mechanisms of action differ widely between distantly related species. To better understand the evolution of piRNAs, we characterized the piRNA pathway in C. briggsae, a sibling species of the model organism C. elegans. Our analyses define 25,883 piRNA producing-loci in C. briggsae. piRNA sequences in C. briggsae are extremely divergent from their counterparts in C. elegans, yet both species adopt similar genomic organization and transcription program that drive piRNA expression. By examining production of Piwi-dependent secondary small RNAs, we identified a set of protein-coding genes that are evolutionarily conserved piRNA targets. In contrast to C. elegans, small RNAs mapped to ribosomal RNAs or histone transcripts are not hyper-accumulated in C. briggsae. Instead, we found that fewer introns in transcripts are associated with hyper-accumulation of small RNAs. Together our work highlights evolutionary conservation and divergence of the nematode piRNA pathway and provides insights into its role in endogenous gene regulation.
2022-08-23 | GSE203297 | GEO
Project description:PIWI-interacting RNAs (piRNAs) promote fertility in many animals. Yet, whether this is due to their conserved role in repressing repetitive elements (REs) or other functions remains unclear. Here, we show that the progressive loss of fertility in Caenorhabditis elegans lacking piRNAs is not caused by derepression of REs or other piRNA targets, but rather mediated by the epigenetic silencing of all the replicative histone genes. In the absence of piRNAs, downstream components of the piRNA pathway relocalize from germ granules and piRNA targets to histone mRNAs to synthesize antisense small RNAs (sRNAs) and induce transgenerational silencing. Removal of the downstream components of the piRNA pathway is sufficient to restore histone mRNA expression and fertility in piRNA mutants, and the inheritance of histone sRNAs in wild-type worms adversely affects their fertility for multiple generations. We conclude that the transgenerational silencing of histone genes contributes to the progressive loss of fertility in piRNA mutants and that coupling piRNAs and histone silencing may serve to maintain piRNAs production across evolution.
2019-12-11 | PXD012557 | Pride
Project description:Parasitism is a major ecological niche for a variety of nematodes. Multiple nematode lineages have specialized as pathogens, including deadly parasites of insects that are used in biological control. We have sequenced and analyzed the draft genomes and transcriptomes of the entomopathogenic nematode Steinernema carpocapsae and four congeners (S. scapterisci, S. monticolum, S. feltiae, S. glaseri) distantly related to Caenorhabditis elegans. We used these genomes to establish phylogenetic relationships, explore gene conservation across species, identify genes uniquely expanded in insect parasites, and to identify conserved non-coding regulatory motifs that influence similar biological processes. Protein domain analysis of these genomes reveals a striking expansion of numerous putative parasitism genes including certain protease and protease inhibitor families as well as fatty acid- and retinol-binding proteins. We identify rapid evolution and expansion of the important developmental Hox gene cluster and identify novel conserved non-coding regulatory motifs associated with orthologous genes in Steinernema and Caenorhabditis. The deep conservation of the network of non-coding DNA motifs between these two genera for a subset of orthologous genes involved in neurogenesis and embryonic development suggests that a kernel of protein-DNA relationships is conserved through nematode evolution. We analyzed the gene expression of a total of 24 RNA-seq samples from 3 nematode species( S. carpocapsae, S. feltiae, and C. elegans) for comparative analysis. We collected the RNA at four developmental time points (mixed embryo, L1, infective juvenile/dauer, young adult) for each species in replicates.
2015-06-05 | E-GEOD-68588 | biostudies-arrayexpress
Project description:Transposable elements are genomic parasites that expand within and spread between genomes. Piwi proteins control transposon activity, notably in the germline. These proteins recognize their targets through small RNA co-factors named piRNAs, making piRNA biogenesis a key specificity-determining step in this important genome immunity system. While the processing of piRNA precursors is an essential step in this process, many molecular details of this process remain unknown. We identify a novel endoribonuclease, PUCH, that initiates piRNA processing in the nematode Caenorhabditis elegans. Genetic and biochemical studies show that PUCH, a trimer of Schlafen-like-domain (SLFNL) proteins, executes 5ï‚¢-end piRNA precursor cleavage. PUCH-mediated processing strictly requires an m7G-Cap and a Uracil at position three. We also demonstrate how PUCH interacts with PETISCO, a complex that binds piRNA precursors, and that this interaction enhances piRNA production in vivo. The identification of PUCH completes the C. elegans piRNA biogenesis repertoire and uncovers a novel type of RNA endonuclease formed by three SLFL proteins. Mammalian Slfn genes have been associated with immunity responses, exposing a novel molecular link between immune responses in mammals and deeply conserved RNA-based mechanisms that control transposable elements.
2023-10-24 | PXD039502 | Pride
Project description:Caenorhabditis. briggsae and Caenorhabditis. nigoni Raw sequence reads
| PRJNA1125123 | ENA
Project description:The nematode Caenorhabditis elegans contains each of the broad classes of eukaryotic small RNAs, including microRNAs (miRNAs), endogenous small-interfering RNAs (endo-siRNAs) and piwi-interacting RNAs (piRNAs). To better understand the evolution of these regulatory RNAs, we deep sequenced small RNAs from C. elegans and three closely related nematodes: C. briggsae, C. remanei and C. brenneri. The results reveal a fluid landscape of small RNA pathways with essentially no conservation of individual sequences aside from a subset of miRNAs. We identified 52 miRNA families that are conserved in each of the four species as well as numerous miRNAs that are species specific or shared between only two or three species. Despite a lack of conservation of individual piRNAs and siRNAs many of the features of each pathway, including genomic distribution, are conserved. We show that in each species, 26G siRNAs trigger stage-specific secondary siRNA formation. We also observe that piRNAs trigger siRNA formation from targets containing up to three mismatches in each species. Finally, we show that nematodes produce two distinct sex-specific classes of piRNAs, suggesting different roles for piRNAs in male and female germlines. Sequencing small RNAs from four Caenorhabditis species: C. elegans, C. briggsae, C. remanei and C. brenneri
2012-10-11 | E-GEOD-41461 | biostudies-arrayexpress
Project description:PIWI-interacting RNAs (piRNAs) promote fertility in many animals. Yet, whether this is due to their conserved role in repressing repetitive elements (REs) remains unclear. Here, we show that the progressive loss of fertility in Caenorhabditis elegans lacking piRNAs is not caused by derepression of REs or other piRNA targets, but rather mediated by the epigenetic silencing of all the replicative histone genes. In the absence of piRNAs, downstream components of the piRNA pathway relocalize from germ granules and piRNA targets to histone mRNAs to synthesize antisense small RNAs (sRNAs) and induce transgenerational silencing. Removal of the downstream components of the piRNA pathway restores histone mRNA expression and fertility in piRNA mutants, and the inheritance of histone sRNAs in wild-type worms adversely affects their fertility for multiple generations. We conclude that the sRNA-mediated silencing of histone genes impairs fertility of piRNA mutants and may serve to maintain piRNAs across evolution.
2019-12-10 | GSE125601 | GEO
Project description:In order to study the similarities and differences in embryonic development between plant-parasitic nematodes and free-living nematodes, we performed RNA-seq on embryos of three plant-parasitic nematodes at a total of 11 stages from the single-cell stage to the J1 stage
2024-05-25 | GSE268038 | GEO