RT Journal Article
SR Electronic
T1 Polycomb Cbx2 Condensates Assemble through Phase Separation
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 468926
DO 10.1101/468926
A1 Roubina Tatavosian
A1 Samantha Kent
A1 Kyle Brown
A1 Tingting Yao
A1 Huy Nguyen Duc
A1 Thao Ngoc Huynh
A1 Chao Yu Zhen
A1 Brian Ma
A1 Haobin Wang
A1 Xiaojun Ren
YR 2018
UL http://biorxiv.org/content/early/2018/11/12/468926.abstract
AB Polycomb group (PcG) proteins are master regulators of development and differentiation. Mutation and dysregulation of PcG genes cause developmental defects and cancer. PcG proteins form condensates in the nucleus of cells and these condensates are the physical sites of PcG-targeted gene silencing. However, the physiochemical principles underlying the PcG condensate formation remain unknown. Here we show that Polycomb repressive complex 1 (PRC1) protein Cbx2, one member of the Cbx family proteins, contains a long stretch of intrinsically disordered region (IDR). Cbx2 undergoes phase separation to form condensates. Cbx2 condensates exhibit liquid-like properties and can concentrate DNA and nucleosomes. We demonstrate that the conserved residues within the IDR promote the condensate formation in vitro and in vivo. We further indicate that H3K27me3 has minimal effects on the Cbx2 condensate formation while depletion of core PRC1 subunits facilitates the condensate formation. Thus, our results reveal that PcG condensates assemble through liquid-liquid phase separation (LLPS) and suggest that PcG-bound chromatin is in part organized through phase-separated condensates.