Jürg Müller on the genetic transmission of gene locks
Propagation of Polycomb-repressed chromatin requires sequence-specific recruitment to DNA.
Friederike Laprell, Katja Finkl and Jürg Müller (2017). Propagation of Polycomb-repressed chromatin requires sequence-specific recruitment to DNA. Science, 356(6333), 85–88. doi:10.1126/science.aai8266
"Epigenetic inheritance models posit that during Polycomb repression, Polycomb repressive complex 2 (PRC2) propagates histone H3 lysine 27 trimethylation (H3K27me3) independently of DNA sequence. We show that insertion of Polycomb response element (PRE) DNA into the Drosophila genome creates extended domains of H3K27me3-modified nucleosomes in the flanking chromatin and causes repression of a linked reporter gene. After excision of PRE DNA, H3K27me3 nucleosomes become diluted with each round of DNA replication, and reporter gene repression is lost. After excision in replication-stalled cells, H3K27me3 levels stay high and repression persists. H3K27me3-marked nucleosomes therefore provide a memory of repression that is transmitted in a sequence-independent manner to daughter strand DNA during replication. In contrast, propagation of H3K27 trimethylation to newly incorporated nucleosomes requires sequence-specific targeting of PRC2 to PRE DNA."
Abstract cited directly from publication.