江苏大学生命科学研究院
国家重点基础研究发展计划(973)(2012CB114600), 国家自然科学基金(31101673), 江苏省高校自然科学基金(10KJB180001), 江苏大学启动基金(09JDG005)资助项目
Institute of Life Sciences,Jiangsu University
This work was supported by grants from National Basic Research Program of China(2012CB114600), The National Natural Science Foundation of China (31101673), Natural Science Foundation for Universities of Jiangsu Province (10KJB180001) and Start-Up Research Funding of Jiangsu University for Distinguished Scholars (09JDG005)
多囊体(multivesicular body,MVB)是由晚期内吞体的限制膜内陷出芽而形成的动态的亚细胞结构,是真核细胞重要的膜和蛋白质运输与分拣中心,并与信号转导、胞质分裂、基因沉默、自噬、蛋白质的质量控制、病毒出芽等密切相关.多囊体生物发生涉及20多种囊泡分拣蛋白(Vps),最重要的是在内吞体膜上形成的4种内吞体运输分拣复合物(ESCRT 0、Ⅰ、Ⅱ、Ⅲ)和Vps4.ESCRT 0与包涵素在内吞体膜上形成微域并富集泛素化的货物蛋白. ESCRTⅠ和Ⅱ诱导MVB囊泡出芽、促进囊泡形成并分拣货物蛋白到囊泡中. ESCRTⅢ收缩及剪切芽颈,完成最后的膜脱落过程.Vps4解离ESCRT以循环利用. 泛素化及泛素化蛋白也能修饰或调控ESCRT的定位及功能.这些研究表明,泛素化蛋白、ESCRT和Vps4在内吞体膜上的相继协同作用是驱动紧密偶联的多囊体生物发生及蛋白质分拣的主要力量.本文以蛋白质-蛋白质相互作用为主,综述了ESCRT复合物及Vps4多聚体的组装机制、相互作用、生理功能以及泛素化蛋白和泛素化对ESCRT的调控,并对下一步研究进行了展望.
Multivesicular body (MVB) is a dynamic subcellular organelle formed by invagination of the limiting membrane of late endosome. MVB is an essential transport and sorting station for membranes and proteins in eukaryotic organisms. MVB pathway is intimately involved in various processes, including signal transduction, cytokinesis, gene silencing, autophagy, protein quality control and virus budding. The biogenesis of MVB requires more than 20 vacuolar protein sorting (Vps) proteins. Many of them can assemble into four distinct complexes ESCRT 0,Ⅰ,Ⅱ,Ⅲ (endosomal sorting complexs required for transport) on the endosomal membrane. ESCRTs and Vps4 are considered to be the most important components in MVB pathway. ESCRT 0 together with clathrin can form microdomain on endosomal membrane where they cluster ubiquitinated cargo proteins. ESCRTⅠ and Ⅱ can induce the budding of intraluminal vesicles (ILVs), prompt the formation process and sort protein cargoes into ILVs. ESCRTⅢ can constrict, cleave the bud neck and finish the membrane abscission, the last stage of MVB formation. Vps4 can disassemble ESCRT complexes and recycle them. Ubiquitinated cargo proteins and ubiquitination can also regulate the localization and function of ESCRTs. Together, these recent discoveries demonstrate that the sequential and co-ordinated actions of ubiquitinated cargo proteins, ESCRTs and Vps4 are the major driving force for the biogenesis of MVB and protein sorting process. In this review, we focus on the protein-protein interaction and mainly discuss the assembly mechanism, interaction and function of ESCRT complexes and Vps4 high-order oligomers, as well as the regulation of ESCRTs by ubiquitinated proteins and ubiquitination. We also suggest prospective studies based on these discussions.
夏恒传,张春霞,冯 凡,袁 弋,周 阳,刘晓勇,朱克明,姚 勤,陈克平.多囊体生物发生和蛋白质分拣——ESCRT、Vps4、Ubiquitination一个都不能少[J].生物化学与生物物理进展,2013,40(2):103-117
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