title: piRNAs--the ancient hunters of genome invaders.
abstract: In addition to miRNAs and siRNAs, a third small RNA silencing system has been uncovered that prevents the spreading of selfish genetic elements. Production of the Piwi-associated RNAs (piRNAs), which mediate the silencing activity in this pathway, is initiated at a few master control regions within the genome. The nature of the primary piRNA-generating transcript is still unknown, but RNA interference (RNAi)-like cleavage events are likely defining the 5'-ends of mature piRNAs. We summarize the recent literature on piRNA biogenesis and function with an emphasis on work in Drosophila, where genetics and biochemistry have met very successfully.
authors.affiliation: Gene Center of the Ludwig-Maximilians-University, D-81377 München, Germany.
authors.forename: Julia Verena
authors.initials: JV
authors.lastname: Hartig
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Tomari
authors.forename: Klaus
authors.initials: K
authors.lastname: Förstemann
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage; D004330:Drosophila / Q000235:genetics / Q000378:metabolism; D020868:Gene Silencing; D016678:Genome; D008957:Models, Genetic; D009154:Mutation; D012313:RNA / Q000235:genetics* / Q000378:metabolism; D020365:RNA Helicases / Q000235:genetics / Q000378:metabolism
chemical_list: D012313:RNA; D020365:RNA Helicases