The Drosophila TART transposon manipulates the piRNA pathway as a counter-defense strategy to limit host silencing

Co-evolution between transposable elements (TEs) and their hosts can be antagonistic, where TEs evolve to avoid silencing and the host responds by reestablishing TE suppression, or mutualistic, where TEs are co-opted to benefit their host. The TE functions as an important component of Drosophila telomeres, but has also reportedly inserted into the nuclear export factor gene . We find that, rather than inserting into has actually captured a portion of sequence. We show that Nxf2 is involved in suppressing activity via the piRNA pathway and that produces abundant piRNAs, some of which are antisense to the transcript. We propose that capturing sequence allowed to target the gene for piRNA-mediated repression and that these two elements are engaged in antagonistic co-evolution despite the fact that is serving a critical role for its host genome.