Su(Hw) Architectural Protein Binding Sites Stimulate Recruitment of PcG/TrxG Epigenetic Regulators to Chromatin: CRISPR/Cas9-Test

Abstract

Polycomb and Trithorax group proteins (PcG and TrxG) are epigenetic factors responsible for the repression and activation of transcription, respectively. In Drosophila, PcG/TrxG proteins are recruited to specialized DNA elements called PRE (Polycomb response elements). Depending on the context, these elements may repress, activate, or be neutral with respect to the promoter of the target gene. Previously, in transgenic studies using PhiC31 site-specific integration system, we have demonstrated that sites for architectural proteins inserted next to PRE can induce the repressive activity of bxdPRE by stimulating the binding of PcG/TrxG factors to this element. However, this effect may depend on additional DNA elements present at the integration site after PhiC31-dependent transgene insertion. In the present study, using an alternative system of integration based on CRISPR/Cas9-catalyzed homology-directed repair, we have proved that the binding sites of the architectural protein Su(Hw) are indeed able to induce the repressive activity of bxdPRE and recruitment of PcG/TrxG proteins, regardless the heterogenous DNA-sequences present at the site of integration after PhiC31-dependent insertion of the transgenes.