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Zebrafish germline small RNAs

ABSTRACT: Piwi proteins specify an animal-specific subclass of the Argonaute family, that in vertebrates are specifically expressed in germ cells. We demonstrate that zebrafish Piwi (Ziwi) is expressed in both the male and the female gonad, and is a component of a germline specifying structure, called nuage. Loss of Ziwi function results in a progressive loss of germ cells due to apoptosis during larval development. In animals that have only reduced Ziwi function, germ cells are maintained, but display abnormal levels of apoptosis in adults. In mammals, Piwi proteins have been found to associate with approximately 29-nucleotide long, testis specific RNA molecules, called piRNAs. Here we show that zebrafish piRNAs are present in both ovaries and testes. Furthermore, we show that piRNAs are modified at their 3’ end and that they are produced by a Dicer independent mechanism. Many ovarian piRNAs are derived from transposons, implicating a role for these molecules in the silencing of these repetitive elements in vertebrates. Keywords: high-throughput 454 sequencing

ORGANISM(S): Danio rerio

PROVIDER: GSE7131 | GEO | 2007/04/05

SECONDARY ACCESSION(S): PRJNA98195

REPOSITORIES: GEO

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Zebrafish germline small RNAs

Project description:Piwi proteins specify an animal-specific subclass of the Argonaute family, that in vertebrates are specifically expressed in germ cells. We demonstrate that zebrafish Piwi (Ziwi) is expressed in both the male and the female gonad, and is a component of a germline specifying structure, called nuage. Loss of Ziwi function results in a progressive loss of germ cells due to apoptosis during larval development. In animals that have only reduced Ziwi function, germ cells are maintained, but display abnormal levels of apoptosis in adults. In mammals, Piwi proteins have been found to associate with approximately 29-nucleotide long, testis specific RNA molecules, called piRNAs. Here we show that zebrafish piRNAs are present in both ovaries and testes. Furthermore, we show that piRNAs are modified at their 3’ end and that they are produced by a Dicer independent mechanism. Many ovarian piRNAs are derived from transposons, implicating a role for these molecules in the silencing of these repetitive elements in vertebrates. Keywords: high-throughput 454 sequencing sequencing of ~30 nt small RNAs from zebrafish ovaries and testes using 454 technology

2007-04-04 | E-GEOD-7131 | biostudies-arrayexpress

Zebrafish Zili- and Ziwi-interacting small RNAs

Project description:Small RNAs exert an effect through diverse RNA interference pathways to transcriptionally or post-transcriptionally silence their targets. The Piwi-interacting RNAs (piRNAs) represent a germline-specific small RNA pathway where Piwi proteins themselves are thought to mediate piRNA biosynthesis. Here, we provide strong evidence for a piRNA amplification loop in zebrafish, in which Ziwi and Zili bind piRNAs of opposite polarity. Furthermore, we describe a function for Zili in transposon defense and germ cell differentiation, as well as a crucial function in meiosis, significantly extending the function of Piwi proteins beyond the control of transposable elements in vertebrates. small RNA from total gonads or Argonaute IPs were cloned and sequenced using 454 GS FLX system.

2008-11-04 | E-GEOD-12547 | biostudies-arrayexpress

Zebrafish Zili- and Ziwi-interacting small RNAs

2008-11-04 | GSE12547 | GEO

Proteomic analysis of murine Piwi proteins reveals a role for arginine methylation in specifying interaction with Tudor family members

Project description:In germ cells, Piwi proteins interact with a specific class of small non-coding RNAs, piwi-interacting RNAs (piRNAs). Together, these form a pathway that represses transposable elements, thus safeguarding germ cell genomes. While basic models describe the operation of piRNA pathways, neither the protein compositions of Piwi complexes, the critical protein-protein interactions that drive small RNA production and target recognition, or the precise molecular consequences of conserved localization to germline structures, call nuage, is well understood. We purified the three murine Piwi family proteins, Mili, Miwi, and Miwi2, from mouse germ cells and characterized their interacting protein partners. Piwi proteins were found in complex with Prmt5/Wdr77, an enzyme that di-methylates arginine residues. By immunoprecipitation with specific antibodies and by mass spectrometry, we found that Piwi proteins are arginine methylated at conserved positions in their amino termini. These modifications are essential to direct complex formation with specific Tudor-domain proteins, whose interactions with Piwis can be required for localization of RNP complexes in cytoplasmic nuage, proper piRNA expression, and transposon silencing. Considered together, our findings indicate that arginine methylation drives the assembly of multi-protein machines whose integrity and specific sub-cellular localization is necessary for efficient function of the piRNA pathway. Keywords: gene regulation study Total small RNA in embryonic and post-birth mouse testes of tdrd1 and tdrd6 mutants

2009-07-25 | E-GEOD-17319 | biostudies-arrayexpress

Maelstrom functions in the production of Siwi-piRISC capable of regulating transposons in Bombyx germ cells

Project description:PIWI-interacting RNAs (piRNAs) bind to PIWI proteins to assemble the piRISC, which represses germline transposons. Maelstrom (Mael) is necessary for piRISC biogenesis in germ cells, but its function remains unclear. Here, we show that Mael interconnects Spindle-E (Spn-E), a key piRISC biogenesis factor, with unloaded Siwi, one of two silkworm PIWI members. Mael also assembles a subset of nuage, a non-membranous organelle involved in piRISC biogenesis. Loss of Mael abrogated the Spn-E–Siwi interaction and Ago3-piRISC biogenesis, but Siwi-piRISC was produced. Bioinformatic analysis showed that Siwi-bound piRNAs in Mael-lacking cells were rich in transposon-targeting piRNAs as in normal cells but were biased toward transposons that are marginally controlled by Siwi-piRISC. This explains the impairment in Ago3-piRISC production because transposon mRNAs cleaved by Siwi are the origin of Ago3-loaded piRNAs. We argue that Mael plays a role in the production of primary Siwi-piRISC capable of regulating transposon expression in germ cells.

2022-03-02 | GSE180191 | GEO

Proteomic analysis of murine Piwi proteins reveals a role for arginine methylation in specifying interaction with Tudor family members

2009-07-25 | GSE17319 | GEO

A trans-generational epigenetic process defines piRNA biogenesis in Drosophila virilis

Project description:Piwi interacting (pi)RNAs repress diverse transposable elements in the germ cells of metazoans and are essential for fertility in both invertebrates and vertebrates. The precursors of piRNAs are transcribed from distinct genomic regions, the so-called piRNA clusters; however, how piRNA clusters are differentiated from the rest of the genome is not known. To address this question, we studied piRNA biogenesis in two Drosophila virilis strains that show differential ability to generate piRNAs from several genomic regions. We found that active piRNA biogenesis correlates with high levels of histone 3 lysine 9 trimethylation (H3K9me3) over genomic regions that give rise to piRNAs. Furthermore, piRNA biogenesis in the progeny requires the trans-generational inheritance of an epigenetic signal, presumably in form of homologous piRNAs that are generated in the maternal germline and deposited into the oocyte. The inherited piRNAs enhance piRNA biogenesis by installment of H3K9me3 mark on piRNA clusters and by promoting ping-pong processing of homologous transcripts into mature piRNAs. We submitted the resequencing data together with the functional genomic datasets because it was generated with the sole purpose of supporting those. The SRA accession numbers are SRR1536176 and SRR1536175. ChIP-seq against H3K9me3 and Pol2, Total RNA-seq, in Drosophila virilis Strain9 and Strain160 as well as crosses between them

2014-09-01 | E-GEOD-59965 | biostudies-arrayexpress

A role for Fkbp6 and the chaperone machinery in piRNA amplification and transposon silencing

Project description:Epigenetic silencing of transposons by Piwi-interacting RNAs (piRNAs) constitutes an RNA-based genome defense mechanism. Piwi endonuclease action amplifies the piRNA pool by generating new piRNAs from target transcripts by a poorly understood mechanism. Here, we identified mouse Fkbp6 as a factor in this biogenesis pathway delivering piRNAs to the Piwi protein Miwi2. Mice lacking Fkbp6 derepress LINE1 (L1) retrotransposon and display reduced DNA methylation due to deficient nuclear accumulation of Miwi2. Like other co-chaperones, Fkbp6 associates with the molecular chaperone Hsp90 via its tetratricopeptide repeat (TPR) domain. Inhibition of the ATP-dependent Hsp90 activity in an insect cell culture model results in the accumulation of short antisense RNAs in Piwi complexes. We identify these to be by-products of piRNA amplification that accumulate only in nuage-localized Piwi proteins. We propose that the chaperone machinery normally ejects these inhibitory RNAs, allowing turnover of Piwi complexes for their continued participation in piRNA amplification.

2012-09-04 | GSE39203 | GEO

Trans-generationally inherited piRNAs trigger piRNA biogenesis by changing the chromatin of piRNA clusters and inducing precursor processing [Rhino RNA-seq]

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. total RNA sequencing of RNA from ovaries of shWhite and Rhino knockdown flies

2014-07-26 | E-GEOD-59607 | biostudies-arrayexpress

Trans-generationally inherited piRNAs trigger piRNA biogenesis by changing the chromatin of piRNA clusters and inducing precursor processing [cuff smallRNA]

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. small RNA (19-29nt) sequencing of RNA from ovaries of cuff+/- or cuff-/- flies

2014-07-26 | E-GEOD-59608 | biostudies-arrayexpress

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