Genomic binding profiling upon expression of AbdA in S2 cells

We sought to determine the genomic binding profile of the Drosophila Hox protein AbdA in a homogenous cell system. S2-DRSC cells that have no Hox expression were stably transfected with HA-tagged AbdA under the control of a metallothionein promoter. Upon AbdA expression, we identified high enrichment of AbdA at a large number transcription start sites that colocalises with the GAGA and M1BP. Genes targeted by GAGA and M1BP contain paused RNA polymerase II and show enrichment of PcG proteins. Upon AbdA binding at M1BP-target sites, a significant reduction in PcG protein binding is observed with a concomitant reduction in RNA Pol II pausing. These data suggest that AbdA targets both GAGA- and M1BP-controlled genes, and at M1BP-controlled genes, AbdA binding is sufficient to release PcG-mediated RNA Pol II pausing to induce gene transcription. S2-DRSC cells are stably transfected with HA-tagged AbdA (S2-DRSC:AbdA). S2 and S2-AbdA cells are analysed for genomic binding of HA-AbdA, Poised RNA Pol II (Rpb3), Elongating RNA Pol II (PolII_phosphoSer2), M1BP, GAGA factor, dRing, E(z), in the absence (S2-DRSC) and presence (S2-DRSC-HA::AbdA) of AbdA