TY - JOUR TI - Differentiating Drosophila female germ cells initiate Polycomb silencing by regulating PRC2-interacting proteins AU - DeLuca, Steven Z AU - Ghildiyal, Megha AU - Pang, Liang-Yu AU - Spradling, Allan C A2 - Levine, Mia T A2 - Tyler, Jessica K A2 - Kassis, Judith A VL - 9 PY - 2020 DA - 2020/08/10 SP - e56922 C1 - eLife 2020;9:e56922 DO - 10.7554/eLife.56922 UR - https://doi.org/10.7554/eLife.56922 AB - Polycomb silencing represses gene expression and provides a molecular memory of chromatin state that is essential for animal development. We show that Drosophila female germline stem cells (GSCs) provide a powerful system for studying Polycomb silencing. GSCs have a non-canonical distribution of PRC2 activity and lack silenced chromatin like embryonic progenitors. As GSC daughters differentiate into nurse cells and oocytes, nurse cells, like embryonic somatic cells, silence genes in traditional Polycomb domains and in generally inactive chromatin. Developmentally controlled expression of two Polycomb repressive complex 2 (PRC2)-interacting proteins, Pcl and Scm, initiate silencing during differentiation. In GSCs, abundant Pcl inhibits PRC2-dependent silencing globally, while in nurse cells Pcl declines and newly induced Scm concentrates PRC2 activity on traditional Polycomb domains. Our results suggest that PRC2-dependent silencing is developmentally regulated by accessory proteins that either increase the concentration of PRC2 at target sites or inhibit the rate that PRC2 samples chromatin. KW - polycomb KW - PRC2 KW - nurse cell KW - differentiation KW - chromatin KW - epigenetic JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -