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Updated: Oct 28, 2025

Repressing Gene Transcription by Redirecting Cellular Machinery with Chemical Epigenetic Modifiers
Published on: September 20, 2018
Polycomb-group recruitment to a Drosophila target gene is the default state that is inhibited by a transcriptional
Elnaz Ghotbi1, Piao Ye1, Taylor Ervin1
1Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275-0376, USA.
Abstract:
Polycomb-group (PcG) proteins are epigenetic regulators that maintain the transcriptional repression of target genes following their initial repression by transcription factors. PcG target genes are repressed in some cells, but active in others. Therefore, a mechanism must exist by which PcG proteins distinguish between the repressed and active states and only assemble repressive chromatin environments at target genes that are repressed. Here, we present experimental evidence that the repressed state of a Drosophila PcG target gene, giant (gt), is not identified by the presence of a repressor. Rather, de novo establishment of PcG-mediated silencing at gt is the default state that is prevented by the presence of an activator or coactivator, which may inhibit the catalytic activity of Polycomb-repressive complex 2 (PRC2).
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