Project description:Animal germ cells produce PIWI-interacting RNAs (piRNAs), small silencing RNAs that suppress transposons and enable gamete maturation. Mammalian transposon-silencing piRNAs accumulate early in spermatogenesis, whereas pachytene piRNAs are produced later during post-natal spermatogenesis and account for >95% of all piRNAs in the adult mouse testis. Mutants defective for pachytene piRNA pathway proteins fail to produce mature sperm, but neither the piRNA precursor transcripts nor the trigger for pachytene piRNA production is known. Here, we show that the transcription factor A-MYB initiates pachytene piRNA production. A-MYB drives transcription of both pachytene piRNA precursor RNAs and the mRNAs for core piRNA biogenesis factors, including MIWI, the protein through which pachytene piRNAs function. A-MYB regulation of piRNA pathway proteins and piRNA genes creates a coherent feed-forward loop that ensures the robust accumulation of pachytene piRNAs. This regulatory circuit, which can be detected in rooster testes, likely predates the divergence of birds and mammals. ChIP sequencing in mouse and rooster testes.
Project description:Belle has been known to be co-localized with piRNA-related proteins at the nuage of germline cells during Drosophila oogenesis. However, its role in piRNA biogenesis remains unclear. To reveal whether Belle is involved in regulating piRNA expression, we performed next-generation sequencing analysis of small non-coding RNAs on ovaries harvested from the wild type (W1118) and trans-heterozygous bel[74407/neo30] mutant. Small RNA-seq experiments were performed on three individual ovary samples with the same genotype. For piRNA expression analysis, we performed mapping of three sets of small RNA sequencing reads for each genotype to previously identified eight distinct piRNA clusters located in four different Drosophila chromosomes (from X to 4). Analysis of the piRNA expression profiling from these piRNA cluster loci indicates that some specific piRNA populations were either upregulated or downregulated in bel mutant ovaries compared with wild-type ovaries. Furthermore, we performed systematic analysis by mapping piRNA sequencing reads to sequences of all identified Drosophila transposable elements (TEs) to classify and measure piRNA reads based on their TE targets. Among 124 TE-classified piRNA populations, 9 and 20 of them were upregulated and downregulated (≥2 folds), respectively, in bel74407/neo30 mutant ovaries compared with those from wild-type ovaries. To examine the effect of the bel[74407/neo30] mutation on the ping-pong cycle for secondary piRNA biogenesis, analysis of the ping-pong signature of piRNAs specifically mapped to the retro-element Burdock was performed. The ping-pong signature for the generation of secondary piRNAs was not significantly altered in bel mutants compared with the wild type. These results, taken together, indicate that Bel is not required for primary and secondary piRNA biogenesis, but it is involved in regulating expression of specific subsets of piRNA populations.
Project description:Piwi-interacting RNA (piRNA) are small RNA abundant in the germline across animal species. In fruit flies and mice, piRNA were implicated in maintenance of genomic integrity by transposable elements silencing. Outside of the germline, piRNA have only been found in Drosophila ovarian follicle cells. Previous studies further reported the presence of multiple piRNA-like small RNA (pilRNA) in fly heads and a small number of pilRNA in mouse tissues and human NK cells. Here, by analyzing high-throughput small RNA sequencing data in more than 130 fruit fly, mouse and rhesus macaque samples, we show widespread presence of pilRNA displaying all known characteristics of piRNA in multiple somatic tissues of these three species. In mouse pancreas and macaque epididymis, pilRNA abundance was compatible with piRNA abundance in the germline. Using in situ hybridizations, we further demonstrate pilRNA co-localization with mRNA expression of Piwi-family genes in all macaque tissues. These findings indicate that piRNA-like molecules might play important roles outside of the germline.
Project description:Exposure to heat waves could result in adverse effects on human health, especially in male testicles. Piwi-interacting RNA (piRNA) is a novel type of small non-coding RNA, which can notably impact mRNA turnover and preserve germline maintenance in germline cells. In this study, a mouse testicular heat stress model was constructed and the testes were removed for piRNA-sequencing. Bioinformatics analysis was used to discover the differential expressed piRNAs, piRNA clusters, and enriched pathways.
Project description:The PIWI-interacting small RNA (piRNA) pathway silences transposons in the germline of almost all animals. Contrary to the conservation of the pathway, piRNA-producing loci turn over fast between species, even though some of these loci are found in syntenic regions and even when the sequences of the piRNA precursor transcripts are conserved. The evolution of piRNAs is a remarkable, yet poorly understood, characteristic of this class of small RNAs. In order to learn about the sequence changes that contribute to the fast evolution of piRNAs, we set out to analyse piRNA expression between genetically different mice. Here we report the sequencing and analysis of small RNAs from the mouse male germline of four classical inbred strains, one inbred wild-derived strain and one outbred strain. We show that the majority of piRNAs are produced from the same loci, with similar levels, in different mice, with notable exceptions. We find that genetic differences between individuals cause variation in piRNA expression from specific loci. We report differences in piRNA production at loci of the mouse genome with endogenous retrovirus insertions in the same strand as the piRNA-precursor transcripts. These results suggest that at least one of the piRNA biogenesis pathways identifies transcripts as piRNA precursors when these transcripts are post-transcriptionally controlled by strand-specific regulatory elements of endogenous retroviruses. Our findings provide evidence that transposable elements are major – although not the only – drivers of piRNA diversification in mammals.
Project description:This study examines the conservation of Piwi-interacting RNA (piRNA) clusters that come from protein coding gene transcripts. By sequencing small RNA libraries from gonad tissues of Drosophilids and Glires we discover a diverse set of genic piRNA clusters conserved across animals. This dataset reveals new expression patterns for genic piRNA clusters and examines whether changing piRNA expression patterns correlates with sequence changes in piRNA cluster genomic sequence across a variety of animal species.
Project description:Small non-coding RNAs that associate with Piwi proteins, called piRNAs, serve as guides for repression of diverse transposable elements in germ cells of Metazoa. In Drosophila, the genomic regions that give rise to piRNAs, the so-called piRNA clusters, are transcribed to generate long precursor molecules that are processed into mature piRNAs. How genomic regions that give rise to piRNA precursor transcripts are differentiated from the rest of the genome and how these transcripts are specifically channeled into the piRNA biogenesis pathway are not known. We found that trans-generationally inherited piRNAs provide the critical trigger for piRNA production from homologous genomic regions in the next generation by two different mechanisms. First, inherited piRNAs enhance processing of homologous transcripts into mature piRNAs by initiating the ping-pong cycle in the cytoplasm. Second, inherited piRNAs induce installment of the H3K9me3 mark on genomic piRNA cluster sequences. The HP1 homolog Rhino binds to the H3K9me3 mark through its chromodomain and is enriched over piRNA clusters. Rhino recruits the piRNA biogenesis factor Cutoff to piRNA clusters and is required for efficient transcription of piRNA precursors. We propose that trans-generationally inherited piRNAs act as an epigenetic memory for identification of substrates for piRNA biogenesis on two levels, by inducing a permissive chromatin environment for piRNA precursor synthesis and by enhancing processing of these precursors. ChIPseq of Rhino and Cutoff in Drosophila melanogaster ovaries The Rhino-BioTAP flies were made by fusing the BioTAP tag (Alekseyenko et al. 2014 )to the C-terminal region of the Rhino gene under the UASp promoter. The Cutoff-EGFP fly line (Nanos-GAL4/UASp-Cutoff-GFP), Cuff^wm25 and Cuff^qq37 were a generous gift from T. Schupbach.
Project description:Animal germ cells produce PIWI-interacting RNAs (piRNAs), small silencing RNAs that suppress transposons and enable gamete maturation. Mammalian transposon-silencing piRNAs accumulate early in spermatogenesis, whereas pachytene piRNAs are produced later during post-natal spermatogenesis and account for >95% of all piRNAs in the adult mouse testis. Mutants defective for pachytene piRNA pathway proteins fail to produce mature sperm, but neither the piRNA precursor transcripts nor the trigger for pachytene piRNA production is known. Here, we show that the transcription factor A-MYB initiates pachytene piRNA production. A-MYB drives transcription of both pachytene piRNA precursor RNAs and the mRNAs for core piRNA biogenesis factors, including MIWI, the protein through which pachytene piRNAs function. A-MYB regulation of piRNA pathway proteins and piRNA genes creates a coherent feed-forward loop that ensures the robust accumulation of pachytene piRNAs. This regulatory circuit, which can be detected in rooster testes, likely predates the divergence of birds and mammals. Transcriptome and ChIP sequencing in mouse and rooster testes
Project description:This SuperSeries is composed of the following subset Series: GSE32180: MIWI catalysis is required for piRNA amplification-independent LINE1 transposon silencing [microarray] GSE32184: MIWI catalysis is required for piRNA amplification-independent LINE1 transposon silencing [deep sequencing] Refer to individual Series
Project description:The proteome of target protein (Armi or Zuc) immunoprecipitation and control immunoprecipitation performed in parallel in three biological replicates, as described in Ge et al., 2019, The RNA-binding ATPase, Armitage, Couples piRNA Amplification in Nuage to Phased piRNA Production on Mitochondria, published in Molecular Cell.