N-terminal acetylation and the N-end rule pathway control degradation of the lipid droplet protein PLIN2
N-terminal acetylation and the N-end rule pathway control degradation of the lipid droplet protein PLIN2
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DOI：
10.1074/jbc.ra118.005556
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发表时间：
2019-01-04
影响因子：
4.8
通讯作者：
Hwang, Cheol-Sang
中科院分区：
文献类型：
--
作者：
Kha The Nguyen;Lee, Chang-Seok;Hwang, Cheol-Sang
periilipin 2 （PLIN2）是一种主要的脂滴（LD）相关蛋白，可调节细胞内脂质稳态和LD形成。在无脂条件下，PLIN2的非结合（自由）形式在细胞质中通过一种未知的泛素(Ub)-蛋白酶体途径被消除，该途径与蛋白质的n端或近n端残基相关。通过HeLa、HEK293T和HepG2人细胞系、环己亚胺追踪、体内泛素化、分裂-Ub酵母双杂交和基于化学交联的互反共免疫沉淀实验，我们发现E3 Ub连接酶和Ac/ n端规则通路的识别组分TEB4 （MARCH6）直接靶向n端乙酰化PLIN2的n端乙酰化片段，使其多泛素化并被26S蛋白酶体降解。我们还发现teb4介导的Ac/ n端规则通路通过降解PLIN2减少细胞内LD积累。总的来说，这些发现确定了PLIN2是Ac/N-end规则通路的底物，并表明Ac/N-end规则通路在LD代谢中的作用以前未被认识到。
Perilipin 2 (PLIN2) is a major lipid droplet (LD)-associated protein that regulates intracellular lipid homeostasis and LD formation. Under lipid-deprived conditions, the LD-unbound (free) form of PLIN2 is eliminated in the cytosol by an as yet unknown ubiquitin (Ub)-proteasome pathway that is associated with the N-terminal or near N-terminal residues of the protein. Here, using HeLa, HEK293T, and HepG2 human cell lines, cycloheximide chase, in vivo ubiquitylation, split-Ub yeast two-hybrid, and chemical cross-linking-based reciprocal co-immunoprecipitation assays, we found that TEB4 (MARCH6), an E3 Ub ligase and recognition component of the Ac/N-end rule pathway, directly targets the N-terminal acetyl moiety of N-terminally acetylated PLIN2 for its polyubiquitylation and degradation by the 26S proteasome. We also show that the TEB4-mediated Ac/N-end rule pathway reduces intracellular LD accumulation by degrading PLIN2. Collectively, these findings identify PLIN2 as a substrate of the Ac/N-end rule pathway and indicate a previously unappreciated role of the Ac/N-end rule pathway in LD metabolism.