piRNAdb: A piwi-interacting RNA database

Abstract Motivation Found in several metazoan species, piwi-interacting RNAs (piRNAs) regulate the expression of a wide variety of transposable elements and genes associated with cellular development, differentiation, and growth. Despite their importance, piRNAs are not well known and are still underexplored. To facilitate piRNA research, a comprehensive and easy-to-use piRNA database is still needed. Results Here, we present piRNAdb, an integrative and user-friendly database designed to encompass several aspects of piRNAs. We selected piRNAs from four reliable human RNA-sequencing datasets to start our database. After data processing, we displayed these sequences, their genomic location, clustering information, putative targets on known genes and transposable elements, as well as direct links to other databases. In this first release, piRNAdb catalogues 27,329 piRNAs, as well as 23,380 genes that are putative targets and 47,060 associated gene ontology terms, both of which are organized and linked to each respective piRNA. Finally, to improve information exchange and increase the confidence of sequences, a feedback system is provided to users of piRNAdb. Conclusion The inclusion of new features to facilitate piRNA analyses, data visualization, and integration is the major pillar of piRNAdb. Our main goal was to make this database an easy interface between the data and the user. We believe that this web tool achieves this objective by providing a streamlined and well-organized data repository for piRNAs and that it will be extremely useful to those already studying piRNAs and to the broader community. Availability piRNAdb is available freely and is compatible with smartphones and tablets: https://www.pirnadb.org/