(375) piRNA Precursor Formation in Mammals

Zuzana Loubalova¹, Parthena Konstantinidou¹, Franziska-Marie Ahrend^1,2, Aleksandr Friman^1,3, Astrid D. Haase¹

1. National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA

2. Regensburg Center for Biochemistry (RCB), Laboratory for RNA Biology, University of Regensburg, Regensburg, Germany

3. Biophysics Graduate Program, University of Maryland, College Park, MD, USA

 


Abstract Text: The piRNA pathway is a conserved small RNA silencing pathway using PIWI proteins loaded with small RNA molecules called piRNAs (PIWI-interacting RNAs). PiRNA pathways function in germ cells of animals to silence transposable genetic elements and protect genome integrity. Mutations in piRNA pathways universally result in impaired germ cell development and sterility. PiRNAs are generated from single-stranded RNA precursors that originate from large genomic intervals called piRNA clusters. The process by which new piRNA clusters emerge and adapt to novel transposable elements remains largely unclear. In this study, we developed a bioinformatic tool to systematically identify and characterize piRNA clusters across various organisms. Our findings suggest that the formation of piRNA clusters in mammals is linked to transcriptional readthrough. We propose a novel mechanism for the generation of new piRNA precursors in response to retroviral infections. Results from our study improve our understanding of how new piRNA clusters emerge to control genomic invaders and protect germ cell development.