Role of JNK/AP-1 signaling pathway in paraquat-induced activation of NLRP3 inflammasome in microglia

Mengju Lan; Kaidong Wang; Min Huang

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Role of JNK/AP-1 signaling pathway in paraquat-induced activation of NLRP3 inflammasome in microglia

VernacularTitle:JNK/AP-1信号通路在百草枯诱导小胶质细胞NLRP3炎症小体活化中的作用
Author: Mengju LAN ¹ ; Kaidong WANG ^{2
,

3} ; Min HUANG ^{2
,

3}
Author Information

1. Department of Occupational Health and Environmental Hygiene, School of Public Health, Yinchuan, Ningxia 750004, China.
2. Department of Occupational Health and Environmental Hygiene, School of Public Health, Yinchuan, Ningxia 750004, China
3. Ningxia Key Laboratory of Environmental Factors and Chronic Disease Control, Ningxia 750004, China.
Publication Type:Experiment
Keywords: paraquat; Parkinson's disease; JNK/AP-1; NLRP3 inflammasome; BV-2 cells; microglia
From: Journal of Environmental and Occupational Medicine 2023;40(6):705-710
CountryChina
Language:Chinese
Abstract: Background Paraquat (PQ) is one of the environmental factors that can cause sporadic Parkinson's disease (PD). Microglia-mediated neuroinflammation plays an important role in the occurrence and development of PD. Our previous studies have found that low doses of PQ can activate BV-2 microglia to the M1 phenotype and exert pro-inflammatory effects, but the associated mechanism is not clear yet. Objective To explore the role of c-Jun N-terminal kinase (JNK)/activator protein 1 (AP-1) signaling pathway in PQ-induced activation of the NOD-like receptor thermal protein domain associated protoin 3 (NLRP3) inflammasome in microglia. Methods An in vitro microglia model was established. The cells were treated with 0, 0.03, 0.06,and 0.12 μmol·L⁻¹ PQ for 24 h, the whole cell protein was extracted. The relative expression levels of JNK, AP-1 constituent proteins (c-Jun, c-Fos), NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), caspasse-1 precursor (pro caspase-1), interleukin-18 (IL-18), and interleukin-1β (IL-1β) were evaluated by Western blotting, to observe the effects of PQ exposure on JNK/AP-1 signaling pathway and NLRP3 inflammasome. After the treatment of 20 μmol·L⁻¹ JNK inhibitor SP600125, the above proteins were detected again, to explore the driving effect of JNK/AP-1 signaling pathway on NLRP3 inflammasome activation. Results After PQ exposure, the relative expression levels of key proteins of JNK, c-Jun, and c-Fos, NLRP3, ASC, and pro caspase-1 in the 0.06 μmol·L⁻¹ PQ group and the 0.12 μmol·L⁻¹ PQ group were higher than those in the 0 μmol·L⁻¹ PQ group (P＜0.05), and the relative expression levels of IL-18 and IL-1β increased with higher exposure (P＜0.05). After the treatment of JNK inhibitor SP600125, the relative expression levels of key proteins of JNK/AP-1 signaling pathway (JNK, c-Jun, and c-Fos), NLRP3 inflammasome (NLRP3, ASC, and Pro caspase-1), and inflammatory factors (IL-18 and IL-1β) in the control group, the 20 μmol·L⁻¹ SP600125 group, and the 20 μmol·L⁻¹ SP600125+0.06 μmol·L⁻¹ PQ group were lower than those in the 0.06 μmol·L⁻¹ PQ group (P＜0.05). Conclusion PQ exposure can activate the JNK/AP-1 signaling pathway and subsequently drive the activation of NLRP3 inflammasome in BV-2 microglia to mediate neuroinflammatory responses..