A Novel Role of Polycomb in Positive Transcription Regulation by Modulating H4K20me1. Drosophila melanogaster

Polycomb group (PcG) proteins were originally shown to play central roles in maintaining heritable gene suppression during the normal development of higher eukaryotes. However, recent studies in Drosophila and mammals imply a potential positive role of PcG proteins in gene transcription with unknown mechanism. Here, for the first time we report Pc-mediated, E(z)/H3K27me3-dependent positive transcription regulation of Ci and Sens, two key transcription factors involved in body plan during normal development. Further mechanistic studies showed that Pc regulates Sens expression by regulating H4K20me1 at Sens locus. More importantly, this mechanism applies to other genes involved in the developmental process. In summary, we report a novel and general transcription regulation mechanism, that is, Pc-mediated, E(z)/H3K27me3-dependent positive transcription regulation by modulating H4K20me1 during development. Overall design: H4K20me1 ChIP-seq dataset was generated in wide type Drosophila third instar larvae wing discs. RNA-seq datasets were generated for wide type, Polycomb RNAi samples.