Project description:piRNAs silence transposons during germline development. In Drosophila, transcripts from heterochromatic clusters are processed into primary piRNAs in the perinuclear nuage. The nuclear DEAD box protein UAP56 has been previously implicated in mRNA splicing and export, whereas the DEAD box protein Vasa has an established role in piRNA production and localizes to nuage with the piRNA binding PIWI proteins Ago3 and Aub. We show that UAP56 colocalizes with the cluster-associated HP1 variant Rhino, that nuage granules containing Vasa localize directly across the nuclear envelope from cluster foci containing UAP56 and Rhino, and that cluster transcripts immunoprecipitate with both Vasa and UAP56. Significantly, a charge-substitution mutation that alters a conserved surface residue in UAP56 disrupts colocalization with Rhino, germline piRNA production, transposon silencing, and perinuclear localization of Vasa. We therefore propose that UAP56 and Vasa function in a piRNA-processing compartment that spans the nuclear envelope.
Project description:The transposon silencing piRNAs are produced from precursors that are encoded by heterochromatic clusters and processed in the perinuclear nuage. We show that the Drosophila nuclear DEAD box protein UAP56, previously implicated in mRNA splicing and nuclear export, co-localizes with the cluster-associated HP1 homologue Rhino. Prominent nuclear foci containing Rhi and UAP56 localize directly across the nuclear envelope from Vasa, a conserved DEAD box protein and core nuage component that is required for piRNA production, and piRNA precursors immunoprecipitate with both UAP56 and Vasa. A uap56 point mutation that prevents UAP56 protein co-localization with Rhino also disrupts nuage organization, transposon silencing, and expression of dual strand piRNA clusters. By contrast, this allele significantly increases ectopic piRNAs from protein coding genes. We therefore propose that UAP56 and Vasa organize a piRNA-processing compartment that spans the nuclear envelope, increasing the efficiency and specificity of piRNA biogenesis.
Project description:The transposon silencing piRNAs are produced from precursors that are encoded by heterochromatic clusters and processed in the perinuclear nuage. We show that the Drosophila nuclear DEAD box protein UAP56, previously implicated in mRNA splicing and nuclear export, co-localizes with the cluster-associated HP1 homologue Rhino. Prominent nuclear foci containing Rhi and UAP56 localize directly across the nuclear envelope from Vasa, a conserved DEAD box protein and core nuage component that is required for piRNA production, and piRNA precursors immunoprecipitate with both UAP56 and Vasa. A uap56 point mutation that prevents UAP56 protein co-localization with Rhino also disrupts nuage organization, transposon silencing, and expression of dual strand piRNA clusters. By contrast, this allele significantly increases ectopic piRNAs from protein coding genes. We therefore propose that UAP56 and Vasa organize a piRNA-processing compartment that spans the nuclear envelope, increasing the efficiency and specificity of piRNA biogenesis. 3 replicates of each sample (uap56, vasa), total RNA samples hybridized to tiling array.
Project description:The transposon silencing piRNAs are produced from precursors that are encoded by heterochromatic clusters and processed in the perinuclear nuage. We show that the Drosophila nuclear DEAD box protein UAP56, previously implicated in mRNA splicing and nuclear export, co-localizes with the cluster-associated HP1 homologue Rhino. Prominent nuclear foci containing Rhi and UAP56 localize directly across the nuclear envelope from Vasa, a conserved DEAD box protein and core nuage component that is required for piRNA production, and piRNA precursors immunoprecipitate with both UAP56 and Vasa. A uap56 point mutation that prevents UAP56 protein co-localization with Rhino also disrupts nuage organization, transposon silencing, and expression of dual strand piRNA clusters. By contrast, this allele significantly increases ectopic piRNAs from protein coding genes. We therefore propose that UAP56 and Vasa organize a piRNA-processing compartment that spans the nuclear envelope, increasing the efficiency and specificity of piRNA biogenesis.
Project description:The transposon silencing piRNAs are produced from precursors that are encoded by heterochromatic clusters and processed in the perinuclear nuage. We show that the Drosophila nuclear DEAD box protein UAP56, previously implicated in mRNA splicing and nuclear export, co-localizes with the cluster-associated HP1 homologue Rhino. Prominent nuclear foci containing Rhi and UAP56 localize directly across the nuclear envelope from Vasa, a conserved DEAD box protein and core nuage component that is required for piRNA production, and piRNA precursors immunoprecipitate with both UAP56 and Vasa. A uap56 point mutation that prevents UAP56 protein co-localization with Rhino also disrupts nuage organization, transposon silencing, and expression of dual strand piRNA clusters. By contrast, this allele significantly increases ectopic piRNAs from protein coding genes. We therefore propose that UAP56 and Vasa organize a piRNA-processing compartment that spans the nuclear envelope, increasing the efficiency and specificity of piRNA biogenesis. RNA-Seq: 3 samples examined: w1118, uap56 mutant un-oxidized, uap56 mutant oxidized RIP-Seq: 6 samples: UAP56-Venus, sz-Venus, and wild type w1 with anti-flag and input control each.
Project description:Reproductive isolation defines species divergence and is linked to adaptive evolution of hybrid incompatibility genes. Hybrids between Drosophila melanogaster and Drosophila simulans are sterile, and phenocopy mutations in the PIWI interacting RNA (piRNA) pathway, which silences transposons and shows pervasive adaptive evolution, and Drosophila rhino and deadlock encode rapidly evolving components of a complex that binds to piRNA clusters. We show that Rhino and Deadlock interact and co-localize in simulans and melanogaster, but simulans Rhino does not bind melanogaster Deadlock, due to substitutions in the rapidly evolving Shadow domain. Significantly, a chimera expressing the simulans Shadow domain in a melanogaster Rhino backbone fails to support piRNA production, disrupts binding to piRNA clusters, and leads to ectopic localization to bulk heterochromatin. Fusing melanogaster Deadlock to simulans Rhino, by contrast, restores localization to clusters. Deadlock binding thus directs Rhino to piRNA clusters, and Rhino-Deadlock co-evolution has produced cross-species incompatibilities, which may contribute to reproductive isolation.
Project description:Piwi-interacting RNAs (piRNAs) silence transposons and maintain genome integrity during germline development. In Drosophila, transposon-rich heterochromatic clusters encode piRNAs either on both genomic strands (dual-strand clusters) or predominantly one genomic strand (uni-strand clusters). Primary piRNAs derived from these clusters are proposed to drive a ping-pong amplification cycle catalyzed by proteins that localize to the perinuclear nuage. We show that the HP1 homolog Rhino is required for nuage organization, transposon silencing, and ping-pong amplification of piRNAs. rhi mutations virtually eliminate piRNAs from the dual-strand clusters and block production of putative precursor RNAs from both strands of the major 42AB dual-strand cluster, but not of transcripts or piRNAs from the uni-strand clusters. Furthermore, Rhino protein associates with the 42AB dual-strand cluster,but does not bind to uni-strand cluster 2 or flamenco. Rhino thus appears to promote transcription of dual-strand clusters, leading to production of piRNAs that drive the ping-pong amplification cycle.