External Seminar - Emilie Brasset, iGReD, Clermont-Ferrand - "Complementary Strategies for Transposon Control in the Germline and Soma: Lessons from Drosophila"

Transposable elements (TEs) pose a significant threat to genome integrity, requiring robust silencing mechanisms across different tissues. The PIWI-interacting RNA (piRNA) pathway plays a crucial role in suppressing TE activity in animal germlines through complex transcriptional and post-transcripitonal regulation to ensure effective TE silencing. This pathway is highly conserved across metazoans, from sponge to mammals, highlighting its fundamental importance in genome defense. Most piRNAs derive from the expression of specific genomic regions called “piRNA clusters”, regions densely populated with full-length and truncated TEs. In Drosophila, certain TEs have evolved the ability to be expressed exclusively in somatic follicular cells surrounding the germline, with some even capable of infecting and transposing within germ cells. This evolutionary pressure has led to the emergence of a distinct piRNA pathway in somatic follicle cells, which is essential for efficiently silencing TE expression in these cells and protecting the germline from potential infection. In this presentation, we will explore the distinct yet complementary mechanisms regulating piRNA pathway activity in Drosophila germline and somatic cells, providing a comprehensive understanding of the molecular and epigenetic controls essential for effective TE silencing.

Invited by Mireille Betermier and Kasia Siudeja