Project description:In Drosophila, Tudor protein and its germline partners, Piwi proteins, are expressed in the brain. However, the potential significance of Tudor in neurobiology has not been explored. Here, we test a hypothesis that Tudor is an essential regulator of post-transcriptional gene expression in the brain where it controls levels of certain RNAs required for brain functions. Specifically, transcriptome of tudor mutant brains is compared with that of wild-type brains using next-generation sequencing (RNA-Seq). The hypothesis that Tudor regulates the same genes in both brain and germline is tested by comparing the transcriptomes from tudor mutant brains and ovaries. This research aims at providing innovative outcomes which may reveal exciting commonalities between the germline and brain and may contribute to our understanding of neurodegenerative disorders and the mechanisms of learning and memory.
Project description:23-29 nt Piwi-interacting RNAs (piRNAs) are crucial components of the ribonucleoprotein complexes which silence the most abundant class of mobile genetic elements in human genome, retrotransposons, in germline (germ) cells. In these cells, antisense piRNAs serve as RNA guides for Piwi proteins, base pairing with transposon RNAs which are subsequently cleaved by Piwi proteins. Germ cells belong to special class of stem cells which ultimately give rise to eggs and sperm and therefore, to next generations. Therefore, piRNAs protect next-generation genomes from devastating mutations caused by transposon insertions. Although, role of piRNAs in germ cells has been studied, functions of piRNAs and their associated proteins in somatic cells are not well understood. Importantly, Piwi proteins are expressed in the fruit fly Drosophila brain and are required for the silencing of transposable elements there, clearly indicating that Piwi-associated piRNAs are involved in this process in the brain. Furthermore, piRNAs have been implicated in the memory formation mechanisms in Aplysia brain. In addition to Piwi proteins, their associated partner, molecular scaffold Tudor protein, participates in piRNA biogenesis in germ cells and it is absolutely required for germline development. However, although tudor gene is expressed in the fly brain, its role in the central nervous system is not understood. In this study, we look at the role of Tudor as an essential player in piRNA biogenesis in Drosophila brain.
Project description:PIWI proteins and their bound piRNAs form the core of a gonad specific small RNA silencing pathway in animals that protects the genome against the deleterious activity of transposable elements. Recent studies linked the piRNA pathway to TUDOR biology, where TUDOR domains of various proteins recognize and bind symmetrically methylated Arginine residues in PIWI proteins. We systematically analyzed the Drosophila TUDOR protein family and identified three previously not characterized TUDOR domain-containing genes (CG4771, CG14303 and CG11133) as essential piRNA pathway members. We characterized CG4771 (Avocado) in detail and demonstrate a critical role for this protein during primary piRNA biogenesis in somatic and germline cells of the ovary. Avocado physically and/or genetically interacts with the primary pathway components Piwi, Armitage, Yb and Zucchini. Avocado also interacts with the Tdrd12 orthologs CG11133 and CG31755, which are essential for primary piRNA biogenesis in the germline and probably functionally replace the related and soma specific factor Yb. small RNA libraries were prepared from total RNA isolation of 8 different genotypes
Project description:PIWI proteins and their bound piRNAs form the core of a gonad specific small RNA silencing pathway in animals that protects the genome against the deleterious activity of transposable elements. Recent studies linked the piRNA pathway to TUDOR biology, where TUDOR domains of various proteins recognize and bind symmetrically methylated Arginine residues in PIWI proteins. We systematically analyzed the Drosophila TUDOR protein family and identified three previously not characterized TUDOR domain-containing genes (CG4771, CG14303 and CG11133) as essential piRNA pathway members. We characterized CG4771 (Avocado) in detail and demonstrate a critical role for this protein during primary piRNA biogenesis in somatic and germline cells of the ovary. Avocado physically and/or genetically interacts with the primary pathway components Piwi, Armitage, Yb and Zucchini. Avocado also interacts with the Tdrd12 orthologs CG11133 and CG31755, which are essential for primary piRNA biogenesis in the germline and probably functionally replace the related and soma specific factor Yb.
Project description:Piwi-interacting RNAs (piRNAs) are gonad-specific small RNAs that provide defence against transposable genetic elements called transposons. Our knowledge of piRNA biogenesis is sketchy, partly due to an incomplete inventory of the factors involved. Here, we identify Tudor domain-containing 12 (TDRD12; also known as ECAT8) as a novel piRNA biogenesis factor in mice. TDRD12 is detected in complexes containing MILI (PIWIL2), its associated primary piRNAs, and TDRD1, all of which are already implicated in secondary piRNA biogenesis. Male mice carrying either a nonsense point mutation (repro23 mice) or a targeted deletion in the Tdrd12 locus are infertile, and de-repress retrotransposons. We find that TDRD12 is dispensable for primary piRNA biogenesis but essential for production of secondary piRNAs that enter MIWI2 (PIWIL4). Cell culture studies with the insect orthologue of TDRD12 suggest a role for the multi-domain protein in mediating complex formation with other participants during secondary piRNA biogenesis. Total small RNA and immunoprecipitated small RNA were purified from mouse testis extract and Bmn4 cells for preparation of high-throughput sequencing libraries.
Project description:Drosophila Piwi-family proteins have been implicated in transposon control. Here, we examine piwi-interacting RNAs (piRNAs) associated with each Drosophila Piwi protein and find that Piwi and Aubergine bind RNAs that are predominantly antisense to transposons, whereas Ago3 complexes contain predominantly sense piRNAs. As in mammals, the majority of Drosophila piRNAs are derived from discrete genomic loci. These loci comprise mainly defective transposon sequences, and some have previously been identified as master regulators of transposon activity. Our data suggest that heterochromatic piRNA loci interact with potentially active, euchromatic transposons to form an adaptive system for transposon control. Complementary relationships between sense and antisense piRNA populations suggest an amplification loop wherein each piRNA-directed cleavage event generates the 5’ end of a new piRNA. Thus, sense piRNAs, formed following cleavage of transposon mRNAs, may enhance production of antisense piRNAs, complementary to active elements, by directing cleavage of transcripts from master control loci. Keywords: small RNA libraries from Drosophila ovaries
Project description:Piwi-interacting RNAs (piRNAs) are gonad-specific small RNAs that provide defence against transposable genetic elements called transposons. Our knowledge of piRNA biogenesis is sketchy, partly due to an incomplete inventory of the factors involved. Here, we identify Tudor domain-containing 12 (TDRD12; also known as ECAT8) as a novel piRNA biogenesis factor in mice. TDRD12 is detected in complexes containing MILI (PIWIL2), its associated primary piRNAs, and TDRD1, all of which are already implicated in secondary piRNA biogenesis. Male mice carrying either a nonsense point mutation (repro23 mice) or a targeted deletion in the Tdrd12 locus are infertile, and de-repress retrotransposons. We find that TDRD12 is dispensable for primary piRNA biogenesis but essential for production of secondary piRNAs that enter MIWI2 (PIWIL4). Cell culture studies with the insect orthologue of TDRD12 suggest a role for the multi-domain protein in mediating complex formation with other participants during secondary piRNA biogenesis.