The Integrity of piRNA Clusters is Abolished by Insulators in the Drosophila Germline
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ABSTRACT:
PROVIDER: PRJNA515474 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR8447880.fastq.gz | Fastqsanger.gz | |||
| SRR8447881.fastq.gz | Fastqsanger.gz | |||
| SRR8447882.fastq.gz | Fastqsanger.gz | |||
| SRR8447877.fastq.gz | Fastqsanger.gz | |||
| SRR8447878.fastq.gz | Fastqsanger.gz |
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Project description:Piwi-interacting RNAs (piRNAs) control transposable element (TE) activity in the germline. piRNAs are produced from single-stranded precursors transcribed from distinct genomic loci, enriched by TE fragments and termed piRNA clusters. The specific chromatin organization and transcriptional regulation of Drosophila germline-specific piRNA clusters ensure transcription and processing of piRNA precursors. TEs harbour various regulatory elements that could affect piRNA cluster integrity. One of such elements is the suppressor-of-hairy-wing (Su(Hw))-mediated insulator, which is harboured in the retrotransposon gypsy. To understand how insulators contribute to piRNA cluster activity, we studied the effects of transgenes containing gypsy insulators on local organization of endogenous piRNA clusters. We show that transgene insertions interfere with piRNA precursor transcription, small RNA production and the formation of piRNA cluster-specific chromatin, a hallmark of which is Rhino, the germline homolog of the heterochromatin protein 1 (HP1). The mutations of Su(Hw) restored the integrity of piRNA clusters in transgenic strains. Surprisingly, Su(Hw) depletion enhanced the production of piRNAs by the domesticated telomeric retrotransposon TART, indicating that Su(Hw)-dependent elements protect TART transcripts from piRNA processing machinery in telomeres. A genome-wide analysis revealed that Su(Hw)-binding sites are depleted in endogenous germline piRNA clusters, suggesting that their functional integrity is under strict evolutionary constraints.
2019-03-15 | GSE125173 | GEO
Project description:Piwi-interacting RNAs (piRNAs) control transposable element (TE) activity in the germline. piRNAs are produced from single-stranded precursors transcribed from distinct genomic loci, enriched by TE fragments and termed piRNA clusters. The specific chromatin organization and transcriptional regulation of Drosophila germline-specific piRNA clusters ensure transcription and processing of piRNA precursors. TEs harbour various regulatory elements that could affect piRNA cluster integrity. One of such elements is the suppressor-of-hairy-wing (Su(Hw))-mediated insulator, which is harboured in the retrotransposon gypsy. To understand how insulators contribute to piRNA cluster activity, we studied the effects of transgenes containing gypsy insulators on local organization of endogenous piRNA clusters. We show that transgene insertions interfere with piRNA precursor transcription, small RNA production and the formation of piRNA cluster-specific chromatin, a hallmark of which is Rhino, the germline homolog of the heterochromatin protein 1 (HP1). The mutations of Su(Hw) restored the integrity of piRNA clusters in transgenic strains. Surprisingly, Su(Hw) depletion enhanced the production of piRNAs by the domesticated telomeric retrotransposon TART, indicating that Su(Hw)-dependent elements protect TART transcripts from piRNA processing machinery in telomeres. A genome-wide analysis revealed that Su(Hw)-binding sites are depleted in endogenous germline piRNA clusters, suggesting that their functional integrity is under strict evolutionary constraints.
| S-EPMC6471301 | biostudies-literature
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:The PIWI-interacting RNA (piRNA) pathway is an important mechanism to suppress transposon activation in the germline that is highly conserved between Drosophila and mammals. This pathway starts from transcribing piRNA clusters to generate long piRNA precursors. The majority of piRNA clusters lacks a conventional promoter, and therefore their transcription is considered to utilize a noncanonical mechanism. However, information regarding transcriptional regulation of piRNA clusters is limited. Here, we report that the fly KAT6 acetyltransferase, Enok, is important for transposon silencing in the germline. Further small RNA-seq analysis revealed that Enok is critical for piRNA production from a specific subset of piRNA clusters including 42AB, one of the two major sources of piRNAs. Enok is the major enzyme for establishing the H3K23ac mark, and was shown to promote gene expression by acetylating H3K23. Surprisingly, our RNA-seq and ChIP-seq/ChIP-qPCR results suggest that Enok regulates expression of genes involved in the piRNA production by H3K23ac-dependent mechanisms, and also promotes transcription at piRNA clusters through H3K23ac-independent pathways. Our co-immunoprecipitation assay further suggests that Enok interacts with RNA polymerase II to facilitate transcription of piRNA clusters. Taken together, our study provides novel insights into the regulation of noncanonical transcription at piRNA clusters and transposon silencing.
2021-01-07 | GSE105099 | GEO
Project description:The PIWI-interacting RNA (piRNA) pathway is an important mechanism to suppress transposon activation in the germline that is highly conserved between Drosophila and mammals. This pathway starts from transcribing piRNA clusters to generate long piRNA precursors. The majority of piRNA clusters lacks a conventional promoter, and therefore their transcription is considered to utilize a noncanonical mechanism. However, information regarding transcriptional regulation of piRNA clusters is limited. Here, we report that the fly KAT6 acetyltransferase, Enok, is important for transposon silencing in the germline. Further small RNA-seq analysis revealed that Enok is critical for piRNA production from a specific subset of piRNA clusters including 42AB, one of the two major sources of piRNAs. Enok is the major enzyme for establishing the H3K23ac mark, and was shown to promote gene expression by acetylating H3K23. Surprisingly, our RNA-seq and ChIP-seq/ChIP-qPCR results suggest that Enok regulates expression of genes involved in the piRNA production by H3K23ac-dependent mechanisms, and also promotes transcription at piRNA clusters through H3K23ac-independent pathways. Our co-immunoprecipitation assay further suggests that Enok interacts with RNA polymerase II to facilitate transcription of piRNA clusters. Taken together, our study provides novel insights into the regulation of noncanonical transcription at piRNA clusters and transposon silencing.
2021-01-07 | GSE105025 | GEO
Project description:The PIWI-interacting RNA (piRNA) pathway is an important mechanism to suppress transposon activation in the germline that is highly conserved between Drosophila and mammals. This pathway starts from transcribing piRNA clusters to generate long piRNA precursors. The majority of piRNA clusters lacks a conventional promoter, and therefore their transcription is considered to utilize a noncanonical mechanism. However, information regarding transcriptional regulation of piRNA clusters is limited. Here, we report that the fly KAT6 acetyltransferase, Enok, is important for transposon silencing in the germline. Further small RNA-seq analysis revealed that Enok is critical for piRNA production from a specific subset of piRNA clusters including 42AB, one of the two major sources of piRNAs. Enok is the major enzyme for establishing the H3K23ac mark, and was shown to promote gene expression by acetylating H3K23. Surprisingly, our RNA-seq and ChIP-seq/ChIP-qPCR results suggest that Enok regulates expression of genes involved in the piRNA production by H3K23ac-dependent mechanisms, and also promotes transcription at piRNA clusters through H3K23ac-independent pathways. Our co-immunoprecipitation assay further suggests that Enok interacts with RNA polymerase II to facilitate transcription of piRNA clusters. Taken together, our study provides novel insights into the regulation of noncanonical transcription at piRNA clusters and transposon silencing.
2021-01-07 | GSE133847 | GEO
Project description:The PIWI-interacting RNA (piRNA) pathway is an important mechanism to suppress transposon activation in the germline that is highly conserved between Drosophila and mammals. This pathway starts from transcribing piRNA clusters to generate long piRNA precursors. The majority of piRNA clusters lacks a conventional promoter, and therefore their transcription is considered to utilize a noncanonical mechanism. However, information regarding transcriptional regulation of piRNA clusters is limited. Here, we report that the fly KAT6 acetyltransferase, Enok, is important for transposon silencing in the germline. Further small RNA-seq analysis revealed that Enok is critical for piRNA production from a specific subset of piRNA clusters including 42AB, one of the two major sources of piRNAs. Enok is the major enzyme for establishing the H3K23ac mark, and was shown to promote gene expression by acetylating H3K23. Surprisingly, our RNA-seq and ChIP-seq/ChIP-qPCR results suggest that Enok regulates expression of genes involved in the piRNA production by H3K23ac-dependent mechanisms, and also promotes transcription at piRNA clusters through H3K23ac-independent pathways. Our co-immunoprecipitation assay further suggests that Enok interacts with RNA polymerase II to facilitate transcription of piRNA clusters. Taken together, our study provides novel insights into the regulation of noncanonical transcription at piRNA clusters and transposon silencing.
2021-01-07 | GSE105031 | GEO
Project description:The PIWI-interacting RNA (piRNA) pathway is an important mechanism to suppress transposon activation in the germline that is highly conserved between Drosophila and mammals. This pathway starts from transcribing piRNA clusters to generate long piRNA precursors. The majority of piRNA clusters lacks a conventional promoter, and therefore their transcription is considered to utilize a noncanonical mechanism. However, information regarding transcriptional regulation of piRNA clusters is limited. Here, we report that the fly KAT6 acetyltransferase, Enok, is important for transposon silencing in the germline. Further small RNA-seq analysis revealed that Enok is critical for piRNA production from a specific subset of piRNA clusters including 42AB, one of the two major sources of piRNAs. Enok is the major enzyme for establishing the H3K23ac mark, and was shown to promote gene expression by acetylating H3K23. Surprisingly, our RNA-seq and ChIP-seq/ChIP-qPCR results suggest that Enok regulates expression of genes involved in the piRNA production by H3K23ac-dependent mechanisms, and also promotes transcription at piRNA clusters through H3K23ac-independent pathways. Our co-immunoprecipitation assay further suggests that Enok interacts with RNA polymerase II to facilitate transcription of piRNA clusters. Taken together, our study provides novel insights into the regulation of noncanonical transcription at piRNA clusters and transposon silencing.
2021-01-07 | GSE154839 | GEO
Project description:Expression of transposable elements in the germline is controlled by Piwi-interacting (pi) RNAs produced by genomic loci termed piRNA clusters and associated with Rhino, a Heterochromatin Protein 1 (HP1) homolog. Previously, we have shown that transgenes containing a fragment of the I retrotransposon form de novo piRNA clusters in the Drosophila germline providing suppression of I-element activity. We noted that identical transgenes located in different genomic sites vary considerably in piRNA production and classified them as “strong” and “weak” piRNA clusters. Here, we investigated what chromatin and transcriptional changes occur at the transgene insertion sites after their conversion into piRNA clusters. We found that the formation of a transgenic piRNA cluster is accompanied by activation of transcription from both genomic strands that likely initiates at multiple random sites. The chromatin of all transgene-associated piRNA clusters contain high levels of trimethylated lysine 9 of histone H3 (H3K9me3) and HP1a, whereas Rhino binding is considerably higher at the strong clusters. None of these chromatin marks was revealed at the “empty” sites before transgene insertion. Finally, we have shown that in the nucleus of polyploid nurse cells, the formation of a piRNA cluster at a given transgenic genomic copy works according to an “all– or– nothing” model: either there is high Rhino enrichment or there is no association with Rhino at all. As a result, genomic copies of a weak piRNA transgenic cluster show a mosaic association with Rhino foci, while the majority of strong transgene copies associate with Rhino and are hence involved in piRNA production.
2018-01-24 | GSE88774 | GEO
Project description:In a broad range of organisms, Piwi-interacting RNAs (piRNAs) have emerged as core components of a surveillance system that protects the genome by silencing transposable and repetitive elements. A vast proportion of piRNAs is produced from discrete genomic loci, termed piRNA clusters. The molecular mechanisms and the factors that govern the expression of these loci are largely unknown. We have preciously shown the Cutoff (Cuff), a protein with similarity to yeast Rai1, is a component of the piRNA pathway. In order to understand the function of the Cuff protein in piRNA production, we produced small RNA libraries from cn, bw (wt) and cuffwm25 mutant ovaties. The analysis of these libraries revealed that approximately 80% of the total piRNA population is depleted in the absence of a functional Cuff protein. We also determined that Cuff is mostly a nuclear protein and is enriched at the level of certain piRNA clusters. Our results point to a role for Cuff in the transcriptional regulation of piRNA generating loci and in the production of the proper piRNA complement during Drosophila oogenesis. piRNA profiling in ovaries from cn, bw and cuffwm25 mutant ovaries
2013-06-07 | E-GEOD-47738 | biostudies-arrayexpress