Polyubiquitin chain-induced p62 phase separation drives autophagic cargo segregation  

作　　者：Daxiao Sun Rongbo Wu Jingxiang Zheng Pilong Li Li YU 

机构地区：[1]State Key Laboratory of Membrane Biology, Tsinghua University-Peking University Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China [2]Beijing Advanced Innovation Center for Structural Biology, Tsinghua University-Peking University Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China [3]State Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University-Peking University Joint Center for Life Sciences, School of Life Science, Center for Nano/Micro-Mechanics and Multidisciplinary Innovation Research, Beijing 100084, China

出　　处：《Cell Research》2018年第4期405-415,共11页细胞研究（英文版）

基　　金：We are grateful to members of the Yu and Li groups for helpful discussions. We thank N. Y. for her kind discussions and suggestions about the paper. We are grateful to Nikon Instruments （Shanghai） and the Tsinghua Cell Biology Core Facility for providing technical support. This research was supported by Ministry of Science and Technology of the People＇s Republic of China （2016YFA0500202 and 2017YFA0503404）, the National Natural Science Foundation of China （31430053 and 31621063）, Natural Science Foundation of China international cooperation and exchange program （31561143002）, and the Independent Research of Tsinghua University （20161080135）.

摘　　要：Misfolded proteins can be degraded by selective autophagy. The prevailing view is that ubiquitin-tagged misfolded proteins are assembled into aggregates by the scaffold protein p62, and the aggregates are then engulfed and degraded by autophagosomes. Here we report that p62 forms droplets in vivo which have liquid-like properties such as high sphericity, the ability to undergo fusion, and recovery after photobleaching. Recombinant p62 does not undergo phase separation in vitro; however, adding a K63 polyubiquitin chain to p62 induces p62 phase separation, which results in enrichment of high-molecular weight ubiquitin signals in p62 droplets. Mixing recombinant p62 with cytosol from p62-/- cells also results in p62 phase separation in a polyubiquitination- dependent manner. Mechanistically, p62 phase separation is dependent on p62 polymerization, the interaction between p62 and ubiquitin, and the valence of the polyubiquitin chain. Moreover, p62 phase separation can be regulated by post-translational modifications such as phosphorylation. Finally, we demonstrate that disease-associated mutations in p62 can affect phase separation. We propose that polyubiquitin chain-induced p62 phase separation drives autophagic cargo concentration and segregation.

关 键 词：AUTOPHAGY Biological techniques 

分 类 号：Q51[生物学—生物化学] V421.1[航空宇航科学与技术—飞行器设计]