The piRNA pathway in planarian flatworms : new model, new insights

Title data

Kim, Iana ; Riedelbauch, Sebastian ; Kuhn, Claus-D.:
The piRNA pathway in planarian flatworms : new model, new insights.
In: Biological Chemistry. Vol. 401 (2020) Issue 10 . - pp. 1123-1141.
ISSN 1437-4315
DOI: https://doi.org/10.1515/hsz-2019-0445

Project information

Abstract in another language

PIWI-interacting RNAs (piRNAs) are small regulatory RNAs that associate with members of the PIWI clade of the Argonaute superfamily of proteins. piRNAs are predominantly found in animal gonads. There, they silence transposable elements, regulate gene expression and participate in DNA methylation, thus orchestrating proper germline development. What is more, PIWI proteins are also indispensable for the maintenance and differentiation capabilities of pluripotent stem cells in free-living invertebrate species with regenerative potential. Thus, PIWI proteins and piRNAs seem to constitute an essential molecular feature of somatic pluripotent stem cells and the germline. In keeping with this hypothesis, both PIWI proteins and piRNAs are enriched in neoblasts, the adult stem cells of planarian flatworms, and their presence is a prerequisite for the proper regeneration and perpetual tissue homeostasis of these animals. The piRNA pathway is required to maintain the unique biology of planarians because, in analogy to the animal germline, planarian piRNAs silence transposable elements and ensure stable genome inheritance. Moreover, planarian piRNAs also contribute to the degradation of numerous protein-coding transcripts, a function that may be critical for neoblasts differentiation. This review gives an overview of the planarian piRNA pathway and of its crucial function in neoblast biology.