多梳蛋白CBX家族在哺乳动物中结构与功能多样性的研究进展

Structural and functional diversity of mammalian CBX proteins

多梳蛋白家族(PcG)是一类重要的表观遗传调控因子,主要参与维持特定基因的转录沉默,与多种干细胞的干性维系、细胞分化、细胞周期的调控、细胞衰老、X染色体失活、基因印记、癌症的发生发展等一系列细胞生理及病理活动密切相关.PcG蛋白主要形成PRC1和PRC2两类多梳蛋白抑制复合体,它们彼此相互协同调控基因的表达.其中Chromobox同源蛋白即CBX蛋白作为PRC1复合体的核心组分协助招募并稳定PRC1到染色质的特定区域.在哺乳动物中,CBX蛋白家族包含5个成员,它们在结构和功能方面既有共性又有特性,本文主要就多梳蛋白CBX家族在哺乳动物中结构与功能多样性的研究进展作一综述.

Polycomb group（PcG） proteins,a family of master epigenetic regulators,regulate gene expression mainly through repression of gene transcription.PcG proteins play crucial roles in controlling a variety of cellular physiological and pathological processes,such as maintenance of stemness,cell differentiation,cell cycle control,cell senescence,X chromosome inactivation,genomic imprinting,tumorigenesis etc.The best characterized proteins complexes composed of PcG proteins are Polycomb repressive complexes 1 and 2（PRC1 and PRC2）.They act synergistically in chromatin recognition and transcription regulation at their common target genes.As one of the core components in PRC1,CBX protein facilitates the recruitment and stabilization of PRC1 to target chromatin.In mammals,there are five CBX homologs.Although there are structural similarities and functional redundancies among CBX proteins,each member does have its unique features which result in their specific functions in a given cell type.In this review,we mainly discuss the up-to-date knowledge about the structural and functional similarity and specificity of the mammalian CBX family proteins.