Wang Rong-Hui, Dai Xue-Jing, Wu Hong, Wang Meng-Die, Deng Ran, Wang Yan, Bu Yan-Hong, Sun Ming-Hui, Zhang Heng
Key Laboratory of Xin'an Medicine, Ministry of Education, Hefei, China.
College of Pharmacy, Anhui University of Chinese Medicine, Hefei, China.
Front Pharmacol. 2020 Dec 8;11:584176. doi: 10.3389/fphar.2020.584176. eCollection 2020.
The activated Gα protein subunit (Gαs) and the inhibitory Gα protein subunit (Gαi) are involved in the signal transduction of G protein coupled receptors (GPCRs). Moreover, the conversion of Gαi/Gαs can couple with sphingosine-1-phosphate receptors (S1PRs) and have a critical role in rheumatoid arthritis (RA). Through binding to S1PRs, sphingosine-1-phosphate (S1P) leads to activation of the pro-inflammatory signaling in rheumatoid arthritis synovial fibroblasts (RASFs). Geniposide (GE) can alleviate RASFs dysfunctions to against RA. However, its underlying mechanism of action in RA has not been elucidated so far. This study aimed to investigate whether GE could regulate the biological functions of MH7A cells by inhibiting S1PR1/3 coupling Gαi/Gαs conversion. We use RASFs cell line, namely MH7A cells, which were obtained from the patient with RA and considered to be the main effector cells in RA. The cells were stimulated with S1P (5 μmol/L) and then were treated with or without different inhibitors: Gαi inhibitor pertussis toxin (0.1 μg/mL), S1PR1/3 inhibitor VPC 23019 (5 μmol/L), Gαs activator cholera toxin (1 μg/mL) and GE (25, 50, and 100 μmol/L) for 24 h. The results showed that GE may inhibit the abnormal proliferation, migration and invasion by inhibiting the S1P-S1PR1/3 signaling pathway and activating Gαs or inhibiting Gαi protein in MH7A cells. Additionally, GE could inhibit the release of inflammatory factors and suppress the expression of cAMP, which is the key factor of the conversion of Gαi and Gαs. GE could also restore the dynamic balance of Gαi and Gαs by suppressing S1PR1/3 and inhibiting Gαi/Gαs conversion, in a manner, we demonstrated that GE inhibited the activation of Gα downstream ERK protein as well. Taken together, our results indicated that down-regulation of S1PR1/3-Gαi/Gαs conversion may play a critical role in the effects of GE on RA and GE could be an effective therapeutic agent for RA.
活化的Gα蛋白亚基（Gαs）和抑制性Gα蛋白亚基（Gαi）参与G蛋白偶联受体（GPCRs）的信号转导。此外，Gαi/Gαs的转换可与1-磷酸鞘氨醇受体（S1PRs）偶联，并在类风湿关节炎（RA）中起关键作用。通过与S1PRs结合，1-磷酸鞘氨醇（S1P）导致类风湿关节炎滑膜成纤维细胞（RASFs）中促炎信号的激活。栀子苷（GE）可减轻RASFs功能障碍以对抗RA。然而，其在RA中的潜在作用机制迄今尚未阐明。本研究旨在探讨GE是否能通过抑制S1PR1/3偶联Gαi/Gαs转换来调节MH7A细胞的生物学功能。我们使用RASFs细胞系，即MH7A细胞，其取自RA患者，被认为是RA中的主要效应细胞。用S1P（5 μmol/L）刺激细胞，然后用或不用不同抑制剂处理：Gαi抑制剂百日咳毒素（0.1 μg/mL）、S1PR1/3抑制剂VPC 23019（5 μmol/L）、Gαs激活剂霍乱毒素（1 μg/mL）和GE（25、50和100 μmol/L），处理24小时。结果表明，GE可能通过抑制S1P-S1PR1/3信号通路并激活Gαs或抑制MH7A细胞中的Gαi蛋白来抑制异常增殖、迁移和侵袭。此外，GE可抑制炎性因子的释放并抑制cAMP的表达，cAMP是Gαi和Gαs转换的关键因子。GE还可通过抑制S1PR1/3并抑制Gαi/Gαs转换来恢复Gαi和Gαs的动态平衡，在某种程度上，我们还证明GE抑制了Gα下游ERK蛋白的激活。综上所述，我们的结果表明S1PR1/3-Gαi/Gαs转换的下调可能在GE对RA的作用中起关键作用，并且GE可能是RA的一种有效治疗剂。
