TY - JOUR TI - Dimerisation of the PICTS complex via LC8/Cut-up drives co-transcriptional transposon silencing in Drosophila AU - Eastwood, Evelyn L AU - Jara, Kayla A AU - Bornelöv, Susanne AU - Munafò, Marzia AU - Frantzis, Vasileios AU - Kneuss, Emma AU - Barbar, Elisar J AU - Czech, Benjamin AU - Hannon, Gregory J A2 - Jensen, Torben Heick A2 - Struhl, Kevin VL - 10 PY - 2021 DA - 2021/02/04 SP - e65557 C1 - eLife 2021;10:e65557 DO - 10.7554/eLife.65557 UR - https://doi.org/10.7554/eLife.65557 AB - In animal gonads, the PIWI-interacting RNA (piRNA) pathway guards genome integrity in part through the co-transcriptional gene silencing of transposon insertions. In Drosophila ovaries, piRNA-loaded Piwi detects nascent transposon transcripts and instructs heterochromatin formation through the Panoramix-induced co-transcriptional silencing (PICTS) complex, containing Panoramix, Nxf2 and Nxt1. Here, we report that the highly conserved dynein light chain LC8/Cut-up (Ctp) is an essential component of the PICTS complex. Loss of Ctp results in transposon de-repression and a reduction in repressive chromatin marks specifically at transposon loci. In turn, Ctp can enforce transcriptional silencing when artificially recruited to RNA and DNA reporters. We show that Ctp drives dimerisation of the PICTS complex through its interaction with conserved motifs within Panoramix. Artificial dimerisation of Panoramix bypasses the necessity for its interaction with Ctp, demonstrating that conscription of a protein from a ubiquitous cellular machinery has fulfilled a fundamental requirement for a transposon silencing complex. KW - piRNA pathway KW - co-transcriptional silencing KW - transposon KW - heterochromatin KW - dimerisation KW - LC8 JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -