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bioRxiv · 10.1101/2022.11.13.516321

The insulating activity of the Drosophila BX-C chromatin boundary Fub-1 is parasegmentally regulated by lncRNA read-through

Ibragimov, A.·Bing, X. Y.·Shidlovskii, Y.·Levine, M.·Georgiev, P.·Schedl, P.
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Abstract

Though long non-coding RNAs (lncRNAs) represent a substantial fraction of the Pol II transcripts in multicellular animals, only a few have known functions. Here we report that the blocking activity of the Bithorax complex (BX-C) Fub-1 boundary is segmentally regulated by its own lncRNA. The Fub-1 boundary is located between the Ultrabithorax (Ubx) gene and the bxd/pbx regulatory domain, which is responsible for regulating Ubx expression in parasegment PS6/segment A1. Fub-1 consists of two hypersensitive sites, HS1 and HS2. HS1 is an insulator while HS2 functions primarily as a lncRNA promoter. To activate Ubx expression in PS6/A1 enhancers in the bxd/pbx domain must be able to bypass Fub-1 blocking activity. We show that expression of the Fub-1 lncRNAs in PS6/A1 from the HS2 promoter inactivates Fub-1 insulating activity. Inactivation is due to readthrough as the HS2 promoter must be directed towards HS1 to disrupt blocking.

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Ibragimov, A., Bing, X. Y., Shidlovskii, Y., Levine, M., Georgiev, P., Schedl, P.. 2022-11-15. The insulating activity of the Drosophila BX-C chromatin boundary Fub-1 is parasegmentally regulated by lncRNA read-through. https://doi.org/10.1101/2022.11.13.516321

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