中文摘要：

多梳蛋白家族（polycomb group proteins,Pc G）是一类在染色质水平上通过表观遗传修饰抑制靶基因转录的调节因子,它在调节细胞周期、DNA修复、细胞分化、衰老和死亡中起到重要作用。CBX4作为Pc G家族中唯一具有SUMO E3连接酶活性的成员,可以作用于多种底物,包括HIPK2、SIP1、Ct BP、CTCF、Dnmt3a和HIF-1α等。底物的SUMO化修饰依赖于特定的结构基础,而且SUMO化的底物功能也会相应发生改变。同时,CBX4还可以被其它分子,如HIPK2,SENP2等进行磷酸化以及去SUMO化等修饰。本篇综述详细阐述了CBX4对底物的SUMO化修饰、自身被修饰及其生物学功能的变化。

英文摘要：

Polycomb group proteins（ Pc Gs） are transcriptional repressors that play important roles in epigenetic regulations of cell cycle,DNA repair,cell differentiation,senescence and death. Pc Gs form two polycomb repressive complexes（ PRC）, PRC1 and PRC2. As a member of PRC1,polycomb chromobox4（ CBX4） is the unique component with known enzymatic activity of a small ubiquitin-like modifier（ SUMO） E3 ligase. The known substrates of CBX4 are HIPK2,SIP1,Ct BP,CTCF,Dnmt3 a and HIF-1α. The sumoylation occurs on specific domains or lysine residues,which brings changes in biological function. The sumoylation of HIPK2 and CTCF strengthens the repression on trancription,while the modification of other substrates attenuates the repression. CBX4 may be modified by other enzymes,including phosphorylation and de-sumoylation by HIPK2 or SENP2. In this review,we summarized the effects and importance of CBX4 medicated sumoylation and chemical modification of itself.