Drosophila Scm self-assembles into PcG bodies to recruit PRC2.1 to target genes during Polycomb silencing initiation.

Drosophila Scm self-assembles into PcG bodies to recruit PRC2.1, facilitating H3K27me3 domain formation during Polycomb silencing initiation.

• Why it matters: Understanding how large, condensed H3K27me3 domains are formed and maintained is incomplete, limiting insights into gene silencing mechanisms crucial for development and cell identity.
• What they did: Using Drosophila nurse cells, the study identified that Scm polymerizes into PcG bodies independently of PRC1 and PRC2, then recruits PRC2 via a direct interaction between Scm-Zf-FCS and Pcl-Tudor domains.
• The result: The Scm-Zf-FCS/Pcl-Tudor interaction is essential for viability and Hox gene regulation, suggesting that regulating Scm polymerization could influence the size and placement of H3K27me3 domains.