RalA exerts an inhibitory effect on IL-1β/IL-18 secretion by blocking NLRP3 inflammasome activation in levornidazole-treated human THP-1 macrophages.
The NLRP3 inflammasome is an important mediator of inflammatory responses and its regulation is an active area of research. RalA is a Ras-like GTPase, which play pivotal roles in the biology of cells. So far, there have been very few studies on RalA regulating inflammatory responses. Bioinformatics analysis predicted that RalA might participate in the regulatory network of NLRP3 inflammasome, which has been confirmed in THP-1 macrophages. After virtual screening of compounds, it was found that levonidazole selected from our virtual small molecule compound library has the potential to bind to RalA. Of note, the interaction of RalA/levornidazole was verified by Surface Plasmon Resonance-Biacore T200, LC/MS analysis and Western blotting analysis. Molecular dynamics simulations revealed that the conformational changes of RalA might be regulated by levornidazole. Additionally, IL-1β/IL-18 secretion from ATP + LPS stimulated THP-1-derived macrophages was RalA-dependently suppressed by levornidazole, suggesting that RalA might have an inhibitory effect on NLRP3 inflammasome activation. The results of co-immunoprecipitation and RalA depletion experiments showed that levornidazole could induce RalA to block the assembly of NLRP3/ASC/pro-caspase-1 complex, thereby reducing the levels of cleaved-caspase-1 and IL-1β/IL-18 secretion. Our study has suggested an anti-inflammatory function of RalA and identified its targeting chemical compound. Overall, this study clarifies a novel pharmacological mechanism by which RalA/levornidazole inhibits NLRP3 inflammasome activation and IL-1β/IL-18 secretion.
['Wang|Xingqi|X|', 'Gou|Lingshan|L|', 'Gao|Yuzhi|Y|', 'Huang|Yuqing|Y|', 'Kuai|Rui|R|', 'Li|Yu|Y|', 'Wang|Yujing|Y|', 'Chen|Yanhong|Y|', 'Li|Jun|J|', 'Cheng|Chao|C|', 'Feng|Zhaojun|Z|', 'Wu|Xuefeng|X|', 'Yao|Ruiqin|R|']
D000818:Animals D005260:Female D006801:Humans D058847:Inflammasomes D020382:Interleukin-18 D053583:Interleukin-1beta D008264:Macrophages D008810:Mice, Inbred C57BL D000071199:NLR Family, Pyrin Domain-Containing 3 Protein D009950:Ornidazole D034741:RNA, Small Interfering D000074084:THP-1 Cells D020725:ral GTP-Binding Proteins
RalA IL-1β/IL-18 NLRP3 THP-1 macrophages Conformational change