Project description:Transposable element (TE) activity is repressed in animal gonads by PIWI-interacting RNAs (piRNAs) produced by piRNA clusters. Current models propose that piRNA clusters are functionally defined by the maternal inheritance of piRNAs produced during the previous generation. Taking advantage of an inactive cluster of P-element derived transgene insertions in Drosophila melanogaster, we show here that raising flies at high temperature (29°C) instead of 25°C results in stable conversion of this locus into an active piRNAs producing one reporting thus the first case of the establishment of an active piRNA cluster by environmental changes and without maternal inheritance of homologous piRNAs.
Project description:Nuclear small RNA pathways safeguard genome integrity by establishing transcription-repressing heterochromatin at transposable elements. This inevitably also targets the transposon-rich source loci of the small RNAs themselves. How small RNA source loci are efficiently transcribed while transposon promoters are potently silenced, is not understood. Here, we show that transcription of Drosophila piRNA clusters—small RNA source loci in animal gonads—is enforced through RNA Polymerase II pre-initiation complex formation within repressive heterochromatin. This is accomplished through the TFIIA-L paralog Moonshiner, which is recruited to piRNA clusters via the Heterochromatin Protein-1 variant Rhino. Moonshiner triggers transcription initiation within piRNA clusters by recruiting the TATA box-binding protein (TBP)-related factor TRF2, an animal TFIID core variant. Thus, transcription of heterochromatic small RNA source loci relies on direct recruitment of the core transcriptional machinery to DNA via histone marks rather than sequence motifs, a concept that we argue is a recurring theme in evolution.
Project description:In animal gonads, 23-30nt long PIWI interacting RNAs (piRNAs) guarantee genome integrity by guiding the sequence specific silencing of selfish genetic elements such as transposons. Two major branches of piRNA biogenesis, namely primary processing and ping-pong amplification, feed into the PIWI clade of Argonaute proteins. Despite our conceptual understanding of piRNA biogenesis, major gaps exist in the mechanistic understanding of the underlying molecular processes as well as in the knowledge of the involved players. Here, we demonstrate an essential role for the female sterility gene shutdown in the piRNA pathway. Shutdown, an evolutionarily conserved co-chaperone of the immunophilin class is the first piRNA biogenesis factor that is essential for all primary and secondary piRNA populations in Drosophila. Based on these findings, we define distinct groups of piRNA biogenesis factors and reveal the core concept of how PIWI family proteins are hard-wired into piRNA biogenesis processes. small-RNA libraries from 2 control samples and 7 knock-down samples of D. mel. ovaries and 2 small-RNA profiles from Piwi IP and Aub IP from OSCs.
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:RNA libraries from immunoprecipitates of Tdrd1, Ziwi and Zili, total testis RNA, total RNA from 3 week old wild-type and tdrd1 mutant gonads.
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.
Project description:We designed this experiment to investigate the transcriptional changes in gonads as a result of sex transformation. Here we performed transcriptional profiling of the ovary transformed into testis from the tra loss of function (XX_tra_lof), testis transformed into ovary from the tra gain of function (XY_tra_gof) and ovary transformed into testis in dsxM gain of function (XX_DsxM_gof/lof) Drosophila melanogaster third instar larvae in biological quadruplicates. In addition, as controls we sequenced ovaries and testes from the female and male wildtype larvae respectively. We constructed polyA+ libraries of the gonads, cleaned off the fatbody and performed 50 bp, stranded single-end RNA-Seq.
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. We dissected gonad tissues consisting of ovaries from wildtype adult Drosophilids (D.melanogaster, D.erecta, D.yakuba, D.virilis) and testes from wildtype pre-pubsecent and adult mouse and rats. Adult testes from rabbits were purchased from Pel-Freez Biologicals. Total or immunopreciptated RNAs were extracted from the pulvirized gonad tissues of Drosophilids and Glires. Small RNAs were purified from these samples, converted into cDNA libraries, and sequenced on an Illumina HiSeq2000.