Xin Sheng-Liang, Pan Xiao-Li, Xu Xiao-Yuan, Yu Yan-Yan
Department of Infectious Diseases, Peking University First Hospital, Beijing, China.
Division of Gastroenterology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
J Clin Transl Hepatol. 2023 Feb 28;11(1):45-57. doi: 10.14218/JCTH.2022.00060. Epub 2022 Mar 31.
Nonalcoholic fatty liver disease (NAFLD) is a common chronic liver disease caused by over-nutrition. Impaired autophagy is closely related to NAFLD progression. Recently, ubiquitin-specific peptidase-10 (USP10) was reported to ameliorate hepatic steatosis, but the underlying mechanism is still unclear. In view of the potential effects of USP10 on autophagy, we investigated whether USP10 alleviated steatosis through autophagy.
HepG2 cells were treated with palmitic acid (PA) to model NAFLD . Lentivirus was used to regulate USP10 level in cells. Autophagic regulators were used to autophagic progression in cells. Western blotting, real-time fluorescence quantitative polymerase chain reaction, lipid drop staining and immunofluorescent staining were performed to determine the effect of USP10 on lipid autophagy. Student's -test and Tukey's post hoc test were used to compare the means among groups.
PA induced cellular steatosis with dependance on autophagy. USP10 overexpression alleviated PA-induced steatosis, restored autophagic activity, promoted autophagic flux, including synthesis and degradation of autophagosomes, and lipid-targeted autophagy. In the presence of autophagy inhibitors, the protective effectiveness of USP10 on steatosis decreased. Furthermore, the specific inhibitor to C-jun N-terminal protein kinase-1 (JNK1), DB07268, abolished USP10-induced autophagy. However, during early stage inhibition of JNK1, compensatory expression of tuberous sclerosis complex-2 (TSC2) maintained autophagy. The degree of TSC2-to-JNK1 compensation was positively associated with USP10 level. Functionally, JNK1 and TSC2 were involved in the lipid-lowering effect of USP10.
USP10 alleviated hepatocellular steatosis in autophagy-dependent manner. JNK1/TSC2 signaling pathways were required for USP10-induced autophagy.
非酒精性脂肪性肝病（NAFLD）是一种由营养过剩引起的常见慢性肝病。自噬受损与NAFLD的进展密切相关。最近，有报道称泛素特异性肽酶10（USP10）可改善肝脂肪变性，但其潜在机制仍不清楚。鉴于USP10对自噬的潜在影响，我们研究了USP10是否通过自噬减轻脂肪变性。
用棕榈酸（PA）处理HepG2细胞以模拟NAFLD。利用慢病毒调节细胞中USP10水平。使用自噬调节剂调节细胞中的自噬进程。进行蛋白质免疫印迹、实时荧光定量聚合酶链反应、脂滴染色和免疫荧光染色以确定USP10对脂质自噬的影响。采用Student's t检验和Tukey事后检验比较各组均值。
PA诱导细胞脂肪变性并依赖于自噬。USP10过表达减轻了PA诱导的脂肪变性，恢复了自噬活性，促进了自噬流，包括自噬体的合成和降解以及脂质靶向自噬。在存在自噬抑制剂的情况下，USP10对脂肪变性的保护作用降低。此外，C-Jun氨基末端蛋白激酶-1（JNK1）的特异性抑制剂DB07268消除了USP10诱导的自噬。然而，在JNK1早期抑制期间，结节性硬化复合物2（TSC2）的代偿性表达维持了自噬。TSC2对JNK1的代偿程度与USP10水平呈正相关。在功能上，JNK1和TSC2参与了USP10的降脂作用。
USP10以自噬依赖的方式减轻肝细胞脂肪变性。USP10诱导的自噬需要JNK1/TSC2信号通路。
