Qu Lingzhi, Guo Ming, Zhang Huajun, Chen Xiaojuan, Wei Hudie, Jiang Longying, Li Jun, Chen Zhuchu, Dai Shuyan, Chen Yongheng
Department of Oncology, NHC Key Laboratory of Cancer Proteomics & State Local Joint Engineering Laboratory for Anticancer Drugs, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, China.
Department of Oncology, NHC Key Laboratory of Cancer Proteomics & State Local Joint Engineering Laboratory for Anticancer Drugs, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, China; Department of Pathology, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, China.
Biochem Biophys Res Commun. 2022 May 21;605:9-15. doi: 10.1016/j.bbrc.2022.03.059. Epub 2022 Mar 12.
Fumarates (fumaric acid esters), primarily dimethyl fumarate (DMF) and monoethyl fumarate (MEF) and its salts, are orally administered systemic agents used for the treatment of psoriasis and multiple sclerosis. It is widely believed that the pharmaceutical activities of fumarates are exerted through the Keap1-Nrf2 pathway. Although it has been revealed that DMF and MEF differentially modify specific Keap1 cysteine residues and result in the differential activation of Nrf2, how the modification of DMF and MEF impacts the biochemical properties of Keap1 has not been well characterized. Here, we found that both DMF and MEF can only modify the BTB domain of Keap1 and that only C151 is accessible for covalent binding in vitro. Dynamic fluorescence scanning (DSF) assays showed that the modification of DMF to Keap1 BTB increased its thermal stability, while the modification of MEF dramatically decreased its thermal stability. Further crystal structures revealed no significant conformational variation between the DMF-modified and MEF-modified BTBs. Overall, our biochemical and structural study provides a better understanding of the covalent modification of fumarates to Keap1 and may suggest fundamentally different mechanisms adopted by fumarates in regulating the Keap1-Nrf2 pathway.
富马酸盐（富马酸酯），主要是富马酸二甲酯（DMF）和富马酸单乙酯（MEF）及其盐类，是口服给药的全身性药物，用于治疗银屑病和多发性硬化症。人们普遍认为富马酸盐的药理活性是通过Keap1-Nrf2途径发挥作用的。尽管已经发现DMF和MEF对Keap1特定半胱氨酸残基的修饰不同，导致Nrf2的激活也不同，但DMF和MEF的修饰如何影响Keap1的生化特性尚未得到很好的表征。在这里，我们发现DMF和MEF都只能修饰Keap1的BTB结构域，并且在体外只有C151可用于共价结合。动态荧光扫描（DSF）分析表明，DMF对Keap1 BTB的修饰提高了其热稳定性，而MEF的修饰则显著降低了其热稳定性。进一步的晶体结构显示，DMF修饰的和MEF修饰的BTB之间没有明显的构象变化。总体而言，我们的生化和结构研究有助于更好地理解富马酸盐对Keap1的共价修饰，并可能揭示富马酸盐在调节Keap1-Nrf2途径中采用的根本不同的机制。
