Nuclear Argonaute Piwi Gene Mutation Affects rRNA by Inducing rRNA Fragment Accumulation, Antisense Expression, and Defective Processing in Ovaries.

key nuclear piRNA silencing pathway protein Piwi of the Argonaute family has been classically studied as a factor controlling transposable elements and fertility. Piwi has been shown to concentrate in the nucleolus for reasons largely unknown. Ribosomal RNA is the main component of the nucleolus. In this work the effect of a mutation on rRNA is described. This work led to three important conclusions: A mutation in induces antisense 5S rRNA expression, a processing defect of 2S rRNA orthologous to the 3'-end of eukaryotic 5.8S rRNA, and accumulation of fragments of all five rRNAs in ovaries. Hypotheses to explain these phenomena are proposed, possibly involving the interaction of the components of the piRNA pathway with the RNA surveillance machinery.