Department of Endocrinology and Metabolism, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Department of Cardiology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Free Radic Biol Med. 2022 Aug 1;188:277-286. doi: 10.1016/j.freeradbiomed.2022.06.237. Epub 2022 Jun 23.
UFMylation is a ubiquitin-like modification which attaches the ubiquitin-fold modifier 1 to target proteins. To date, only a few UFMylation targets have been identified. In the current study, we demonstrated that P4HB is a new target protein for UFMylation and it can be UFMylated at three lysine residues in the form of mono-UFMylation. P4HB has oxidoreductase, chaperone and isomerase effects. It presents in the endoplasmic reticulum, mitochondria and cytosol. Next, we generated a stable HepG2 cell line, the hepatocellular cells, with defective P4HB UFMylation. Our data show that P4HB UFMylation defect promotes P4HB protein degradation via the ubiquitin-proteasome pathway. Defective P4HB UFMylation causes mitochondrial function damage, oxidative stress, and endoplasmic reticulum stress in HepG2 cells. These effects are more obvious when treating HepG2 cells with palmitic acid, which is frequently used as one of the cell models of non-alcoholic fatty liver disease (NAFLD). Our results identify UFMylation as a key post-translational modification for the maintenance of P4HB stability and biological functions in HepG2 cells, and point to P4HB UFMylation as a potential direction in the study of NAFLD.
泛素样蛋白（UFM1）修饰是一种将泛素折叠修饰物 1（UFM1）连接到靶蛋白的泛素样修饰。迄今为止，只有少数 UFMylation 靶标被鉴定出来。在本研究中，我们证明了 P4HB 是 UFMylation 的一个新靶蛋白，它可以在三个赖氨酸残基上以单 UFMylation 的形式被 UFMylation。P4HB 具有氧化还原酶、伴侣和异构酶的作用。它存在于内质网、线粒体和细胞质中。接下来，我们生成了一个稳定的 HepG2 细胞系，即肝细胞，其 P4HB 的 UFMylation 缺陷。我们的数据表明，P4HB 的 UFMylation 缺陷通过泛素-蛋白酶体途径促进 P4HB 蛋白降解。P4HB 的 UFMylation 缺陷导致 HepG2 细胞中线粒体功能损伤、氧化应激和内质网应激。当用棕榈酸处理 HepG2 细胞时，这些效应更为明显，棕榈酸通常被用作非酒精性脂肪性肝病（NAFLD）的细胞模型之一。我们的结果表明，UFMylation 是维持 HepG2 细胞中 P4HB 稳定性和生物学功能的关键翻译后修饰，并指出 P4HB 的 UFMylation 可能是 NAFLD 研究的一个潜在方向。
