Jiangsu Key Laboratory of Bioactive Natural Product Research and State Key Laboratory of Natural Medicines, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing 210009, China; School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin, China.
Jiangsu Key Laboratory of Bioactive Natural Product Research and State Key Laboratory of Natural Medicines, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing 210009, China.
Int Immunopharmacol. 2023 Feb;115:109689. doi: 10.1016/j.intimp.2023.109689. Epub 2023 Jan 6.
SQSTM1/p62 sequesters intracellular aberrant proteins and mediates their selective autophagic degradation. p62 oligomerization posttranslational modification enhances its sequestration function and positively regulates the KEAP1-NRF2 redox pathway. However, the regulation of p62 covalent oligomerization has yet been poorly characterized. Here, we identified a natural small-molecule sesquiterpene, Iso-seco-tanapartholide (IST) modified p62 cysteine residues, which induced p62 to form crosslinked oligomers between TBS and TBS or TBS and PB1 domains in a covalently non-disulfide-linked manner. Using LC-MS/MS analysis and complementary approaches, we revealed that Cys residues of p62 were necessary for IST-induced covalent oligomer. This oligomerization promoted p62 recruitment of KEAP1 for degradation by autophagosomes and released NRF2 to the nucleus to activate the expression of downstream genes with anti-oxidant and anti-inflammatory capacities. Accordingly, IST-mediated p62/NRF2 activation conferred protection from oxidative and inflammatory destruction of rheumatoid arthritis in vitro and in vivo. In contrast, p62-knockdown cells displayed a reduced anti-oxidant response and increased pro-inflammatory cytokine secretion in response to TNF-α stimulation. Hence, our findings uncover an unrecognized role of IST in the regulation of p62 oligomerization and provide a new strategy for the treatment of rheumatoid arthritis.
SQSTM1/p62 隔离细胞内异常蛋白，并介导其选择性自噬降解。p62 的寡聚化翻译后修饰增强了其隔离功能，并正向调节 KEAP1-NRF2 氧化还原途径。然而，p62 共价寡聚化的调节尚未得到很好的描述。在这里，我们鉴定了一种天然的小分子倍半萜，异-贝壳杉烷-16,17-二烯-19-酸内酯（IST），修饰了 p62 的半胱氨酸残基，诱导 p62 在 TBS 和 TBS 或 TBS 和 PB1 结构域之间形成交联寡聚物，以共价非二硫键连接的方式。通过 LC-MS/MS 分析和补充方法，我们揭示了 p62 的半胱氨酸残基对于 IST 诱导的共价寡聚是必需的。这种寡聚化促进了 p62 募集 KEAP1 被自噬体降解，并将 NRF2 释放到核内，激活具有抗氧化和抗炎能力的下游基因的表达。因此，IST 介导的 p62/NRF2 激活赋予了类风湿关节炎体外和体内氧化和炎症破坏的保护作用。相比之下，p62 敲低细胞在 TNF-α刺激下显示出抗氧化反应减弱和促炎细胞因子分泌增加。因此，我们的研究结果揭示了 IST 在调节 p62 寡聚化中的一个未被认识的作用，并为类风湿关节炎的治疗提供了一种新策略。
Zotero 插件