Chromatin binding and transcriptional regulation by TrxG proteins

In Drosophila, both PcG and TrxG proteins are recruited to Polycomb or Trithorax response elements (PREs/TREs). In mammalian cells, unmethylated CpG islands provide docking sites for both types of complexes in response to transcriptional cues. While PcG proteins are recruited to non-transcribed genes, TrxG complexes are recruited to actively transcribed genes, where they contribute to maintaining an open, permissive chromatin environment through nucleosome remodeling and H3K4 methylation. With their opposing functions on chromatin states and mutual inhibition of their respective binding or catalytic function, it appears that the outcome on transcriptional activity depends on the achieved balance of repressive vs activating signals^1,2.

See the full guide for more details on molecular mechanisms underlying the recruitment of TrxG proteins.

References

1. Piunti, A., Shilatifard, A. Epigenetic balance of gene expression by Polycomb and COMPASS families Science 352 , (2016)
2. Bracken, A. P., Brien, G. L., Verrijzer, C. P. Dangerous liaisons: interplay between SWI/SNF, NuRD, and Polycomb in chromatin regulation and cancer Genes Dev 33 ,936-959 (2019)