Somatic piRNA pathway prevents transgenerational germline transposition [circularDNA-seq]

Transposable elements (TEs) are genomic parasite that threat genome integrity. One major strategy organisms evolved to balance TE activity in the germline is the Piwi-interacting RNAs (piRNAs) pathway. It prevents transposition by repressing TE at transcriptional and/or post-transcriptional level. However, evidence that TE derepression caused by piRNA pathway impairment is actually followed by bursts of transposition is still lacking. Here we present a genome-wide TE-analyses of the replicative TE life cycle (their expression, their translation to their transposition in the germline) after piRNA pathway impairment in the somatic follicle cells. We observed a high transposition-rate in the germline, leading to a 10-fold increase in genomic TE-load after 70 successive generations of piRNA pathway impairment. Moreover, we demonstrate that siRNAs co-regulate TE activity at post transcriptional level in follicle cells. These observations demonstrate that the small RNA-mediated TE repression in follicle cells contribute to genome homeostasis. Analysis of effects of conditional piwi knock down in somatic follicle cells on TE behaviour and progeny genome.