Divergent composition and transposon-silencing activity of small RNAs in mammalian oocytes
Ontology highlight
ABSTRACT:
ORGANISM(S): Capra hircus Mesocricetus auratus Rattus norvegicus Mus musculus Danio rerio Sus scrofa domesticus Cavia porcellus Canis lupus familiaris Homo sapiens Oryctolagus cuniculus Macaca fascicularis Cricetulus griseus
PROVIDER: GSE200470 | GEO | 2024/03/06
REPOSITORIES: GEO
Similar Datasets
Project description:We found piRNAs with different lengths represented the predominant small RNA species in oocytes from the 12 explored species, except mouse. We found endo-siRNAs resulted from the truncated Dicer isoform were mouse-specific, and os-piRNAs associating with PIWIL3 in human oocytes are widespread in mammals and are typically with low levels of the 2’-3’-O-methylation. The sequences of many highly expressed piRNA clusters are fast-evolving compared with their syntenic genomic locations, and the TE families distributing in the conserved piRNA clusters are various between species.
2024-03-06 | GSE256514 | GEO
Project description:Germ cells of most animals critically depend on piRNAs and Piwi proteins. Surprisingly, piRNAs in mouse oocytes are relatively rare and dispensable. We present compelling evidence for strong Piwi-piRNA expression in oocytes of other mammals. Human fetal oocytes express PIWIL2 and transposon-enriched piRNAs. Oocytes in adult human ovary express PIWIL1 and PIWIL2, while those in bovine ovary just express PIWIL1. In human, macaque and bovine ovaries we find piRNAs that resemble testis-borne pachytene piRNAs. Isolated bovine follicular oocytes were shown to contain abundant, relatively short piRNAs that preferentially target transposable elements. Using label-free quantitative proteome analysis we show that these maturing oocytes strongly and specifically express the thus-far uncharacterized PIWIL3 protein, alongside other known piRNA-pathway components. In bovine early embryos these piRNAs are still abundant, revealing a potential impact of piRNAs on mammalian embryogenesis. Our results reveal unexpected, highly dynamic piRNA pathways in mammalian oocytes and early embryos. Analyses of multiple small RNA libraries obtained from fetal/adult oocytes, cumulus cells, ovary, testis and 2-4 cell stage ivf embryos of multiple mammalian species.
2015-03-27 | E-GEOD-64942 | biostudies-arrayexpress
Project description:Germ cells of most animals critically depend on piRNAs and Piwi proteins. Surprisingly, piRNAs in mouse oocytes are relatively rare and dispensable. We present compelling evidence for strong Piwi-piRNA expression in oocytes of other mammals. Human fetal oocytes express PIWIL2 and transposon-enriched piRNAs. Oocytes in adult human ovary express PIWIL1 and PIWIL2, while those in bovine ovary just express PIWIL1. In human, macaque and bovine ovaries we find piRNAs that resemble testis-borne pachytene piRNAs. Isolated bovine follicular oocytes were shown to contain abundant, relatively short piRNAs that preferentially target transposable elements. Using label-free quantitative proteome analysis we show that these maturing oocytes strongly and specifically express the thus-far uncharacterized PIWIL3 protein, alongside other known piRNA-pathway components. In bovine early embryos these piRNAs are still abundant, revealing a potential impact of piRNAs on mammalian embryogenesis. Our results reveal unexpected, highly dynamic piRNA pathways in mammalian oocytes and early embryos.
2015-03-27 | GSE64942 | GEO
Project description:PIWI-clade Argonaute proteins silence transposon expression in animal gonads. Their target specificity is defined by bound ~23-30nt piRNAs that are processed from single-stranded precursor transcripts via two distinct pathways. Primary piRNAs are defined by the endo-nuclease Zucchini, while biogenesis of secondary piRNAs depends on piRNA-guided transcript cleavage and results in piRNA amplification. Here, we analyze the inter-dependencies between these piRNA biogenesis pathways in the developing Drosophila ovary. We show that secondary piRNA-guided target slicing is the predominant mechanism that specifies transcripts—including those from piRNA clusters—as primary piRNA precursors and that defines the spectrum of Piwi-bound piRNAs in germline cells. Post-transcriptional silencing in the cytoplasm therefore enforces nuclear, transcriptional target silencing, which ensures the tight suppression of transposons during oogenesis. As target slicing also defines the nuclear piRNA pool during mouse spermatogenesis, our findings uncover an unexpected conceptual similarity between the mouse and fly piRNA pathways.
2015-08-31 | GSE71775 | GEO
Project description:The control of transposable element (TE) activity in germ cells provides genome integrity over generations. A distinct small RNA-mediated pathway utilizing Piwi-interacting RNAs (piRNAs) suppresses TE expression in gonads of metazoans. In the fly, primary piRNAs derive from so-called piRNA clusters, which are enriched in damaged repeated sequences. These piRNAs launch a cycle of TE and piRNA cluster transcript cleavages resulting in the amplification of piRNA and TE silencing. Using genome-wide comparison of TE insertions and ovarian small RNA libraries from two Drosophila strains, we found that individual TEs inserted into euchromatic loci form novel dual-stranded piRNA clusters. Formation of the piRNA-generating loci by active individual TEs provides a more potent silencing response to the TE expansion. Like all piRNA clusters, individual TEs are also capable of triggering the production of endogenous small interfering (endo-si) RNAs. Small RNA production by individual TEs spreads into the flanking genomic regions including coding cellular genes. We show that formation of TE-associated small RNA clusters can down-regulate expression of nearby genes in ovaries. Integration of TEs into the 3' untranslated region of actively transcribed genes induces piRNA production towards the 3'-end of transcripts, causing the appearance of genic piRNA clusters, a phenomenon that has been reported in different organisms. These data suggest a significant role of TE-associated small RNAs in the evolution of regulatory networks in the germline. The fractions of small RNAs (19-29 nt) from ovaries of y[1]; cn[1] bw[1] sp[1] line of Drosophila melanogaster were sequenced using Illumina HiSeq 2000.
2014-02-07 | E-GEOD-46105 | biostudies-arrayexpress
Project description:The control of transposable element (TE) activity in germ cells provides genome integrity over generations. A distinct small RNA-mediated pathway utilizing Piwi-interacting RNAs (piRNAs) suppresses TE expression in gonads of metazoans. In the fly, primary piRNAs derive from so-called piRNA clusters, which are enriched in damaged repeated sequences. These piRNAs launch a cycle of TE and piRNA cluster transcript cleavages resulting in the amplification of piRNA and TE silencing. Using genome-wide comparison of TE insertions and ovarian small RNA libraries from two Drosophila strains, we found that individual TEs inserted into euchromatic loci form novel dual-stranded piRNA clusters. Formation of the piRNA-generating loci by active individual TEs provides a more potent silencing response to the TE expansion. Like all piRNA clusters, individual TEs are also capable of triggering the production of endogenous small interfering (endo-si) RNAs. Small RNA production by individual TEs spreads into the flanking genomic regions including coding cellular genes. We show that formation of TE-associated small RNA clusters can down-regulate expression of nearby genes in ovaries. Integration of TEs into the 3' untranslated region of actively transcribed genes induces piRNA production towards the 3'-end of transcripts, causing the appearance of genic piRNA clusters, a phenomenon that has been reported in different organisms. These data suggest a significant role of TE-associated small RNAs in the evolution of regulatory networks in the germline.
2014-02-07 | GSE46105 | GEO
Project description:PIWI proteins and their guiding Piwi-interacting small RNAs (piRNAs) are crucial for fertility and transposon defense in the animal germline. In most species, the majority of piRNAs are produced from distinct large genomic loci, called piRNA clusters. It is assumed that germline-expressed piRNA clusters, particularly in Drosophila, act as master regulators to control the activity of transposons dispersed across the genome. Here, using synteny analysis, we show that large germline clusters are evolutionarily labile, arise at loci characterized by recurrent chromosomal rearrangements, and are mostly species-specific across the Drosophila genus. By engineering chromosomal deletions in D. melanogaster, we demonstrate that the three largest germline clusters, which the generation of >40% of all transposon-targeting piRNAs depend on, are neither required for fertility nor for the regulation of transposon activity in trans. We provide further evidence that dispersed active elements, rather than the regulatory action of large Drosophila germline clusters in trans, may be central for transposon defense.
2021-05-31 | GSE174561 | GEO
Project description:Small RNAs have important functions. However, small RNAs in primate oocytes remain unexplored. Herein, we develop CAS-seq, a single-cell small RNA sequencing method, and profiled the small RNAs in human oocytes and embryos. We discover a class of ~20-nt small RNAs that are predominantly expressed in human and monkey oocytes, but not in mouse oocytes. They are specifically associated with HIWI3 (PIWIL3), whereas significantly shorter than the commonly known PIWI-interacting RNAs (piRNAs), designated as oocyte short piRNAs (os-piRNAs). Notably, the os-piRNAs in human oocytes lack 2’-O-methylation at the 3’ end, a hallmark of the classic piRNAs. In addition, the os-piRNAs have a strong 1U/10A bias and are enriched on the antisense strands of recently evolved transposable elements (TEs), indicating the potential function of silencing TEs by cleavage. Therefore, our study has identified an oocyte-specific piRNA family with distinct features and provides valuable resources for studying small RNAs in primate oocytes.
2019-06-13 | GSE95218 | GEO
Project description:PIWI-clade Argonaute proteins silence transposon expression in animal gonads. Their target specificity is defined by bound ~23-30nt piRNAs that are processed from single-stranded precursor transcripts via two distinct pathways. Primary piRNAs are defined by the endo-nuclease Zucchini, while biogenesis of secondary piRNAs depends on piRNA-guided transcript cleavage and results in piRNA amplification. Here, we analyze the inter-dependencies between these piRNA biogenesis pathways in the developing Drosophila ovary. We show that secondary piRNA-guided target slicing is the predominant mechanism that specifies transcripts—including those from piRNA clusters—as primary piRNA precursors and that defines the spectrum of Piwi-bound piRNAs in germline cells. Post-transcriptional silencing in the cytoplasm therefore enforces nuclear, transcriptional target silencing, which ensures the tight suppression of transposons during oogenesis. As target slicing also defines the nuclear piRNA pool during mouse spermatogenesis, our findings uncover an unexpected conceptual similarity between the mouse and fly piRNA pathways. To understand the hierarchical order of primary versus secondary piRNA biogenesis in Drosophila ovaries, we sequenced piRNAs bound to total-Piwi, germline-Piwi, Aubergine and Argonaute3 from ovaries of germline specific knockdowns of control, piwi, aub, ago3 single knockdowns and aub/ago3 double knockdowns. To determine changes in Transposable Element (TE) transcription or TE RNA steady state in perturbed piRNA pathway conditions, we performed Pol2-ChIP-sequencing and polyA bound RNA-sequencing from ovaries of multiple germline knockdown genotypes. We also sequenced genomic DNA from ovaries of control knockdowns to experimentally estimate the TE copy number in our genetic background. Finally, we used CAP-seq from germline specific Piwi depletions to identify the Transcriptional Start Sites (TSS) in TEs in a deregulated background. Replicates are labeled with R1, R2, R3, R4 where indicated.
2015-08-31 | E-GEOD-71775 | biostudies-arrayexpress
Project description:The piRNA pathway is a small RNA-based immune system that silences mobile genetic elements in animal germlines. In Drosophila ovaries, piRNAs are produced from discrete genomic loci, called piRNA clusters, which are composed of inactive transposon copies and fragments and thus constitute a genetically encoded memory of past transposon challenges. Two types of piRNA clusters exist in flies: dual-strand clusters, expressed only in the germline via a highly specialised machinery, and uni-strand cluster, which are predominantly expressed in the somatic follicle cells. Flamenco (flam) is the major uni-strand piRNA cluster in Drosophila, giving rise to the majority of somatic piRNAs. Flam resembles a canonical RNA polymerase II transcriptional unit, nonetheless it can be specifically recognised by the piRNA pathway and directed to the biogenesis machinery. Recent work has implicated the RNA helicase Yb in the licensing of somatic piRNA production, however a detailed understanding of the molecular mechanisms underlying flam export and specification is still lacking. Here, we show that flam export triggers the assembly of peri-nuclear condensates of Yb and provide evidence that piRNA production from flam specifically requires subunits of the Nuclear Pore Complex (NPC). In the absence of some NPC subunits, transposons become de-silenced and piRNA biogenesis is compromised exclusively from flam. We also show that Yb transiently associates with the NPC to promote flam export. Taken together, our data shed light on how the export of uni-strand cluster transcripts is achieved and suggest the evolution of a specialised machinery that couples transcription, nuclear export and piRNA production.
2021-04-16 | PXD019671 | Pride