Project description:Uridylation of diverse RNA species represents an emerging theme in post-transcriptional gene regulation. In the microRNA pathway, such modifications regulate small RNA biogenesis and stability in plants, worms and mammals. Here, we report the first uridylyltransferase that acts on small RNAs in Drosophila, which we refer to as Tailor. Tailor is the source for the majority of 3´ end-modifications in microRNAs and predominantly targets precursor-hairpins. Uridylation modulates the characteristic two-nucleotide 3´ overhangs of microRNA hairpins, which regulates processing by Dicer-1 and destabilizes RNA hairpins. Furthermore, Tailor preferentially uridylates mirtron-hairpins, thereby impeding the production of non-canonical microRNAs. Mirtron-selectivity is explained by unique primary sequence specificity of Tailor, selecting RNA substrates ending with a 3´ guanosine, a feature not previously observed for TUTases. In contrast to mirtrons, conserved Drosophila pre-miRNAs are significantly depleted in 3´ guanosine, thereby escaping regulatory uridylation. Our data support the hypothesis that evolutionary adaptation to pre-miRNA uridylation shapes the nucleotide composition of pre-miRNA 3´ ends. Hence, hairpin-uridylation may serve as a barrier for the de novo creation of miRNAs in Drosophila.
Project description:Uridylation of diverse RNA species represents an emerging theme in post-transcriptional gene regulation. In the microRNA pathway, such modifications regulate small RNA biogenesis and stability in plants, worms and mammals. Here, we report the first uridylyltransferase that acts on small RNAs in Drosophila, which we refer to as Tailor. Tailor is the source for the majority of 3´ terminal uridine-modifications in small RNAs and predominantly targets precursor-miRNAs. Uridylation modulates the characteristic two-nucleotide 3´ overhangs of miRNA hairpins, which regulates pre-miRNA processing by Dicer-1. Furthermore, Tailor preferentially uridylates mirtron hairpins, thereby impeding the production of non-canonical microRNAs. Mirtron-selectivity is explained by unique primary sequence specificity of Tailor, selecting RNA substrates ending with a 3´ guanosine, a feature not previously observed for terminal uridylyltransferases. In contrast to mirtrons, conserved Drosophila pre-miRNAs are significantly depleted in 3´ guanosine, thereby escaping regulatory uridylation.Our data support the hypothesis that evolutionary adaptation to pre-miRNA uridylation shapes the nucleotide composition of pre-miRNA 3´ ends and may serve as a barrier for the de novo creation of miRNAs in Drosophila.
Project description:The Dox meiotic drive system distorts the sex-ratio in Drosophila simulans. Here, the authors reconstruct the step-wise emergence, and recent amplification of Dox superfamily genes in parallel with the emergence of autosomal hairpin RNA-class siRNA loci that target subsets of these putative drivers
Project description:miRNAs are small, non-coding RNAs that regulate gene expression post-transcriptionally. We used small RNA sequencing to identify tissue-specific miRNAs in the adult brain, thorax, gut and fat body of Drosophila melanogaster. One of the most brain-specific miRNAs that we identified was miR-210, an evolutionarily highly conserved miRNA implicated in the regulation of hypoxia in mammals. In Drosophila, we show that miR-210 is specifically expressed in sensory organs including photoreceptors. miR-210 knock-out mutants are not sensitive towards hypoxia but show progressive degradation of photoreceptor cells, accompanied by decreased photoreceptor potential, demonstrating an important function of miR-210 in photoreceptor maintenance and survival.