Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109-0650, USA.
Mol Cell Biol. 2011 May;31(10):2100-10. doi: 10.1128/MCB.05088-11. Epub 2011 Mar 14.
Polycomb group (PcG) proteins control the epigenetic inheritance of transcription regulatory states during development. Progression from pluripotency to differentiation requires the concurrent activation and repression of different PcG target genes. We found that REST and nine REST-associated proteins copurified with Cbx family PcG proteins from mouse embryonic stem (ES) cells. REST interacted with Cbx proteins in live cells and coprecipitated with endogenous Ring1b. Endogenous PRC1 subunits occupied all sites tested that were bound by REST in ES cells. Antibodies directed against different PRC1 subunits precipitated proximal versus distal RE1 elements with opposite relative efficiencies, suggesting that PRC1 bound different sites in distinct configurations. Deletion of the amino-terminal region of REST (Rest(ΔN) knockout) as well as short hairpin RNA depletion of REST (REST knockdown) in ES cells reduced PRC1 binding at distal RE1 elements and increased PRC1 binding at proximal RE1 elements. Rest(ΔN) and PRC1 subunit knockout as well as REST and PRC1 subunit knockdown had similar relative effects on transcription of neuronal genes in ES cells, derepressing genes with distal, but not genes with proximal, RE1 elements. In differentiating neurons, Rest(ΔN) knockout reduced PRC1 occupancy and derepressed transcription at distal RE1 elements but increased PRC1 occupancy and repressed transcription at proximal RE1 elements. The opposite effects of REST on PRC1 occupancy at different RE1 elements contributed to the gene-specific control of PRC1 functions during ES cell differentiation.
多梳抑制复合物（PcG）蛋白在发育过程中控制转录调控状态的表观遗传遗传。从多能性向分化的进展需要不同 PcG 靶基因的同时激活和抑制。我们发现 REST 和九个 REST 相关蛋白与 Cbx 家族 PcG 蛋白从小鼠胚胎干细胞（ES 细胞）共纯化。REST 在活细胞中与 Cbx 蛋白相互作用，并与内源性 Ring1b 共沉淀。内源性 PRC1 亚基占据了在 ES 细胞中被 REST 结合的所有测试位点。针对不同 PRC1 亚基的抗体沉淀近端与远端 RE1 元件，相对效率相反，表明 PRC1 以不同的构象结合不同的位点。REST 的氨基末端区域缺失（Rest(ΔN) 敲除）以及 ES 细胞中 REST 的短发夹 RNA 耗竭（REST 敲低）减少了 PRC1 在远端 RE1 元件上的结合，并增加了 PRC1 在近端 RE1 元件上的结合。在 ES 细胞中，Rest(ΔN)和 PRC1 亚基敲除以及 REST 和 PRC1 亚基敲低对神经元基因的转录具有相似的相对影响，解除了具有远端 RE1 元件的基因的抑制，但没有解除具有近端 RE1 元件的基因的抑制。在分化的神经元中，Rest(ΔN)敲除减少了 PRC1 占据并解除了远端 RE1 元件的转录抑制，但增加了 PRC1 占据并抑制了近端 RE1 元件的转录。REST 对不同 RE1 元件上的 PRC1 占据的相反影响有助于 ES 细胞分化过程中 PRC1 功能的基因特异性控制。
