Dynamic coupling of R-loops with transcriptional pausing modulates tissue development in Drosophila

The R-loop in the genome participates in modulating transcription, replication and DNA damage repair, yet its regulation and biologic impact on development in vivo remain to be explored. Here, we modified CUT&Tag strategy and established R-loop profiles of Drosophila across multiple developmental stages. While lack of GC preference, the broad class of R-loops in Drosophila all highly follow the RNAPII pausing, which is also a conserved R-loop regulatory mechanism in mammals. Meanwhile, RNAPII-regulated R-loop may be regulated by multiple developmental specificity and universality transcription factors. To test the specificity and universality of transcription factor-mediated R-loop involvement in development, we knocked out the transcription elongation factor Spt6, upregulated R-loop and increased RNAPII pausing, and altered the expression of critical genes and cutin genes, thereby affecting Drosophila lifespan and cutin development. Interestingly, complementation of rnh1 could partially rescue the transcription factor deletion phenotype. We conclude that RNAPII is a conserved mechanism of R-loop regulation across species and organism specific damage caused by R-loop dysregulation is mediated by the functions of transcription factors. Overall design: To explore the regulatory mechanism of R-loop in Drosophila and embryonic development, we constructed a multi-temporal R-loop map of embryonic development. As well as pol2-chip-seq, RNA-seq and cut&tag before and after interfering transcription factor spt6