Abstract：
Paraquat (PQ) poisoning leads to irreversible fibrosis in the lungs with high mortality and no known antidote. In this study, we investigated the effect of the SET and MYND domain containing 2 (SMYD2) on PQ-induced pulmonary fibrosis (PF) and its potential mechanisms. We established an in vivo PQ-induced PF mouse model by intraperitoneal injection of PQ (20 mg/kg) and in vitro PQ (25 μM)-injured MLE-12 cell model. On the 15th day of administration, tissue injury, inflammation, and fibrosis in mice were evaluated using various methods including routine blood counts, blood biochemistry, blood gas analysis, western blotting, H&E staining, ELISA, Masson staining, and immunofluorescence. The findings indicated that AZ505 administration mitigated tissue damage, inflammation, and collagen deposition in PQ-poisoned mice. Mechanistically, both in vivo and in vitro experiments revealed that AZ505 treatment suppressed the PQ-induced epithelial-mesenchymal transition (EMT) process by downregulating GLI pathogenesis related 2 (GLIPR2) and ERK/p38 pathway. Further investigations demonstrated that SMYD2 inhibition decreased GLIPR2 methylation and facilitated GLIPR2 ubiquitination, leading to GLIPR2 destabilization in PQ-exposed MLE-12 cells. Moreover, rescue experiments conducted in vitro demonstrated that GLIPR2 overexpression eliminated the inhibitory effect of AZ505 on the ERK/p38 pathway and EMT. Our results reveal that the SMYD2 inhibitor AZ505 may act as a novel therapeutic candidate to suppress the EMT process by modulating the GLIPR2/ERK/p38 axis in PQ-induced PF.
摘要：
百草枯（PQ）中毒导致肺部不可逆转的纤维化，死亡率高，没有已知的解毒剂。在这项研究中,我们研究了SET和MYND结构域包含2（SMYD2）对PQ诱导的肺纤维化（PF）的影响及其潜在机制。我们通过腹膜内注射PQ（20mg/kg）和体外PQ（25μM）损伤的MLE-12细胞模型建立了体内PQ诱导的PF小鼠模型。在给药的第15天，组织损伤,炎症,和纤维化小鼠使用各种方法进行评估，包括常规血细胞计数，血液生物化学,血气分析,西方印迹,H&E染色,ELISA,Masson染色,和免疫荧光。研究结果表明，AZ505给药减轻了组织损伤，炎症,和PQ中毒小鼠的胶原沉积。机械上,体内和体外实验均表明，AZ505治疗通过下调GLI发病机制相关2（GLIPR2）和ERK/p38途径来抑制PQ诱导的上皮-间质转化（EMT）过程。进一步的研究表明，SMYD2抑制降低GLIPR2甲基化并促进GLIPR2泛素化，在暴露于PQ的MLE-12细胞中导致GLIPR2不稳定。此外，体外进行的拯救实验表明，GLIPR2过表达消除了AZ505对ERK/p38途径和EMT的抑制作用。我们的结果表明，SMYD2抑制剂AZ505可以通过调节PQ诱导的PF中的GLIPR2/ERK/p38轴来抑制EMT过程。
