Long first exons and epigenetic marks distinguish conserved pachytene piRNA clusters from other mammalian genes
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA616264 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR11448423_1.fastq.gz | Fastqsanger.gz | |||
| SRR11448423_2.fastq.gz | Fastqsanger.gz | |||
| SRR11448424_1.fastq.gz | Fastqsanger.gz | |||
| SRR11448424_2.fastq.gz | Fastqsanger.gz | |||
| SRR11448425_1.fastq.gz | Fastqsanger.gz |
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Project description:In the male germ cells of eutherian animals, 26–30-nt-long PIWI-interacting RNAs (piRNAs) emerge when spermatocytes enter the pachytene phase of meiosis. These pachytene piRNAs derive from ~100 discrete autosomal loci resemble canonical protein-coding genes and long non-coding RNA-producing genes—they are transcribed by RNA polymerase II, bearing 5´ caps and 3´ poly(A) tails, and their transcripts often contain introns that are removed before nuclear export and processing into piRNAs. However, it is unclear which genic and epigenetic features distinguish pachytene piRNA genes from other types of genes and dictate their germline-specific expression. We report that an unusually long first exon (≥ 10 kb) or a long gene absent of introns altogether is highly correlated with both the germline-specific production of piRNA precursor transcripts from mouse pachytene piRNA loci. We also found that these precursor transcripts are enriched in the binding by THOC1 (also known as HPR1) and THOC2, subunits of the THO complex critical for transcription elongation and nuclear export of mRNAs. Our integrative analysis of transcriptome, piRNA, and epigenome datasets across multiple species reveals that a long first exon is an evolutionarily conserved feature of pachytene piRNA loci. We further found that a highly methylated promoter, often containing a low or intermediate level of CG dinucleotides, correlates with germline expression and somatic silencing of pachytene piRNA loci.
2020-10-24 | GSE147724 | GEO
Project description:In the male germ cells of placental mammals, 26-30-nt-long PIWI-interacting RNAs (piRNAs) emerge when spermatocytes enter the pachytene phase of meiosis. In mice, pachytene piRNAs derive from ~100 discrete autosomal loci that produce canonical RNA polymerase II transcripts. These piRNA clusters bear 5' caps and 3' poly(A) tails, and often contain introns that are removed before nuclear export and processing into piRNAs. What marks pachytene piRNA clusters to produce piRNAs, and what confines their expression to the germline? We report that an unusually long first exon (≥ 10 kb) or a long, unspliced transcript correlates with germline-specific transcription and piRNA production. Our integrative analysis of transcriptome, piRNA, and epigenome datasets across multiple species reveals that a long first exon is an evolutionarily conserved feature of pachytene piRNA clusters. Furthermore, a highly methylated promoter, often containing a low or intermediate level of CG dinucleotides, correlates with germline expression and somatic silencing of pachytene piRNA clusters. Pachytene piRNA precursor transcripts bind THOC1 and THOC2, THO complex subunits known to promote transcriptional elongation and mRNA nuclear export. Together, these features may explain why the major sources of pachytene piRNA clusters specifically generate these unique small RNAs in the male germline of placental mammals.
| S-EPMC7782496 | biostudies-literature
Project description:Piwi proteins and Piwi-interacting small RNAs (piRNAs) have known functions in transposon silencing in the male germline of fetal and newborn mice. Both are also necessary for spermatogenesis in adult testes, however, their function here remains a mystery. Here, we use germ cell isolations and small RNA sequencing to show that most piRNAs in meiotic spermatocytes originate from clusters in intergenic non-repeat regions of DNA. The regulation of these piRNA clusters, including the processing of the precursor transcripts into individual piRNAs, is accomplished through mostly unknown processes. We present evidence for a regulatory mechanism for one such cluster, named cluster 1082B, located on chromosome 7 in the mouse genome, containing 788 unique piRNAs. The precursor transcript and individual piRNAs within the cluster are repressed by the Alkbh1 dioxygenase and the transcription repressor Tzfp, which are believed to be interaction partners in testis. We observe more than a thousand-fold upregulation of individual piRNAs in pachytene spermatocytes isolated from Alkbh1-/- and TzfpGTi/GTi testes. Repression is further supported by the identification of a 10 bp Tzfp recognition sequence contained within the precursor transcript. Downregulation of long interspersed elements 1 (LINE1) and intracisternal A-particle (IAP) transcripts in the Alkbh1-/- and TzfpGTi/GTi testes leads us to propose a potential role for the 1082B-encoded piRNAs in transposon silencing. Characterization of small RNAs in mouse pachytene spermatocytes for wild-type (WT) and Alkbh1-/- and TzfpGTi/GTi, and mRNA in mouse pachytene spermatocytes for wild-type (WT) and Alkbh1-/-
2012-09-11 | E-GEOD-37150 | biostudies-arrayexpress
Project description:The origin and stability of germline noncoding RNAs remain largely uncharacterized in mammals. Here, we demonstrate that the vast majority of pachytene piRNAs originate from less than 100 bi- and unidirectionally transcribed loci in the mouse genome. These loci show features characteristic of transcribed protein-coding genes, including primary transcription by RNA polymerase II, H3K4 trimethylation marking the transcription initiation site, and H3K36 trimethylation present at elongation regions in a highly tissue-specific manner. We identified MYBL1, a spermatocyte-enriched transcription factor, as a potential driver of piRNA precursor transcripts. By similarly mapping piRNA clusters in testes of dog and opossum, we revealed that the regulatory architectures generating piRNAs appear to be highly conserved in mammals. Finally, we discovered that apparently neutral chromosomal rearrangements in evolution can act as an unexpected mechanism to generate novel piRNA clusters in diverse mammals. Thus, our results demonstrate how an integrated, multi-species approach can help define the genomic features and evolutionary mechanisms underlying mammalian germline noncoding RNAs.
2015-09-01 | E-MTAB-1265 | biostudies-arrayexpress
Project description:In the fetal mouse testis, PIWI Interacting RNAs (piRNAs) guide PIWI proteins to silence transposons, but after birth, most post-pubertal pachytene piRNAs map to genome uniquely and are thought to regulate genes required for male fertility. In human males, the developmental classes, precise genomic origins, and transcriptional regulation of post-natal piRNAs remain undefined. Here, we demarcate the genes and transcripts that produce post-natal piRNAs in human juvenile and adult testes. As in mouse, A‑MYB in humans drives transcription of both pachytene piRNA precursor transcripts and the mRNAs encoding piRNA biogenesis factors. Although human piRNA genes are syntenic to those in other placental mammals, their sequences are poorly conserved. In fact, pachytene piRNA loci are rapidly diverging even among modern humans. Our findings suggest that during mammalian evolution, pachytene piRNA genes are under fewer selective constraints. We speculate that pachytene piRNA diversity may provide a hitherto unrecognized driver of reproductive isolation.
2019-12-23 | GSE135791 | GEO
Project description:Purpose: piRNAs are a class of germline-specific, small non-coding RNAs required to maintain genome integrity and preserve RNA homeostasis essential for male gametogenesis. During mouse spermatogenesis, male germ cells transcribe piRNAs at pre-pachytene anad pachytene stages of development from genetically distince loci. The most well-studied and conserved function of pre-pachytene piRNAs is repression of transposons to ensure the integrity of the germline genome. In contrast to pre-pachytene piRNAs, the mode of action and function of pachytene piRNA is much less understood. To investigate and characterize the functional importance of pachytene piRNAs in spermatogenesis and male fertility, we have used CRISPR/Cas9 and established mutant mice which have deleted a bi-directional promoter of the pachytene piRNA cluster on Chr18. Mutant mice have a male sterile phenotype with acrosome overgrowth and defective motility.
2019-08-30 | GSE136603 | GEO
Project description:Pachytene piRNAs control male fertility across metazoans, yet mechanisms through which they govern meiosis I in pachytene remain unclear. We demonstrate, in C. elegans, that homolog pairing, and crossover formation are compromised in the absence of piRNA function. We identify several protein coding genes as targets of piRNAs including Polo like kinase 3 (PLK-). Pachytene piRNAs spatially restrict and exclude PLK-3 expression from meiosis I. Expansion of PLK-3 expression into the pachytene region, upon loss of piRNAs, is reflected in meiotic defects, which are partially rescued by removal of ectopic PLK-3. Pachytene piRNAs regulate PLK-3 through both translational repression and post-transcriptional degradation establishing the spatiotemporal control of gene expression. Given the conserved role of pachytene piRNAs, we propose that these mechanisms may be applicable to mammals.
2023-10-14 | GSE245023 | GEO
Project description:Piwi-interacting small RNAs (piRNAs) of fetal prospermatogonia of mice have been strongly implicated in transposon control. In contrast, little is known about biogenesis and function of abundant piRNAs from adult testes expressed in late spermatocytes and round spermatids. These so-called "pachytene" piRNAs are processed from long non-coding piRNA precursors and have no defined RNA targets in the transcriptome even though their binding partner Piwi, MIWI, is essential for spermiogenesis and fertility. Here we report that 129SvJae mice lacking Maelstrom (MAEL), a conserved piRNA pathway protein, exhibit spermiogenic arrest with defects in acrosome and flagellum formation. Further analysis revealed MAEL association with RNPs containing MIWI, TDRD6, and processed intermediates of pachytene piRNA precursors of various length. Loss of MAEL causes a 10-fold drop in pachytene piRNA levels but an increase in piRNAs from abundantly expressed mRNAs. These results suggest a MAEL-dependent mechanism for the selective processing of pachytene piRNA precursor into piRNAs. Strikingly, ribosome profiling of Mael-null testes revealed that reduced piRNA production is accompanied by reduced translation of over 800 spermiogenic mRNAs including those encoding acrosome and flagellum proteins. In light of recent reports of piRNA-independent protection of translationally repressed mRNPs by MIWI and piRNA-dependent turnover of MIWI, we propose that pachytene piRNAs function by controlling the availably of MIWI for the translational repression of spermiogenic mRNAs.
2014-07-25 | GSE50983 | GEO
Project description:Ribosomes guide pachytene piRNA formation on long intergenic piRNA precursors
| PRJNA275185 | ENA
Project description:Piwi proteins and Piwi-interacting small RNAs (piRNAs) have known functions in transposon silencing in the male germline of fetal and newborn mice. Both are also necessary for spermatogenesis in adult testes, however, their function here remains a mystery. Here, we use germ cell isolations and small RNA sequencing to show that most piRNAs in meiotic spermatocytes originate from clusters in intergenic non-repeat regions of DNA. The regulation of these piRNA clusters, including the processing of the precursor transcripts into individual piRNAs, is accomplished through mostly unknown processes. We present evidence for a regulatory mechanism for one such cluster, named cluster 1082B, located on chromosome 7 in the mouse genome, containing 788 unique piRNAs. The precursor transcript and individual piRNAs within the cluster are repressed by the Alkbh1 dioxygenase and the transcription repressor Tzfp, which are believed to be interaction partners in testis. We observe more than a thousand-fold upregulation of individual piRNAs in pachytene spermatocytes isolated from Alkbh1-/- and TzfpGTi/GTi testes. Repression is further supported by the identification of a 10 bp Tzfp recognition sequence contained within the precursor transcript. Downregulation of long interspersed elements 1 (LINE1) and intracisternal A-particle (IAP) transcripts in the Alkbh1-/- and TzfpGTi/GTi testes leads us to propose a potential role for the 1082B-encoded piRNAs in transposon silencing.
2012-09-11 | GSE37150 | GEO