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Background:Lipoxin A4 (LXA4) can alleviate lipopolysaccharide (LPS)-induced acute lung injury (ALI) and acute respiratory distress syndrome through promoting epithelial sodium channel (ENaC) expression in lung epithelial cells.However,how LXA4 promote ENaC expression is still largely elusive.The present study aimed to explore genes and signaling pathway involved in regulating ENaC expression induced by LXA4.Methods:A549 cells were incubated with LPS and LXA4,or in combination,and analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) of ENaC-o/γ.Candidate genes affected by LXA4 were explored by transcriptome sequencing ofA549 cells.The critical candidate gene was validated by qRT-PCR and West blot analysis ofA549 cells treated with LPS and LXA4 at different concentrations and time intervals.LXA4 receptor (ALX) inhibitor BOC-2 was used to test induction of candidate gene by LXA4.Candidate gene siRNA was adopted to analyze its influence on A549 viability and ENaC-α expression.Phosphoinositide 3-kinase (PI3K) inhibitor LY294002 was utilized to probe whether the PI3K signaling pathway was involved in LXA4 induction of candidate gone expression.Results:The A549 cell models of ALI were constructed and subjected to transcriptome sequencing.Among candidate genes,N-myc downstream-regulated gene-1 (NDRG 1) was validated by real-time-PCR and Westem blot.NDRG 1 mRNA was elevated in a dose-dependent manner of LXA4,whereas BOC-2 antagonized NDRG 1 expression induced by LXA4.NDRG 1 siRNA suppressed viability of LPS-treated A549 cells (treatment vs.control,0.605 ± 0.063 vs.0.878 ± 0.083,P =0.040) and ENaC-α expression (treatment vs.control,0.458 ± 0.038 vs.0.711 ± 0.035,P =0.008).LY294002 inhibited NDRG1 (treatment vs.control,0.459 ± 0.023 vs.0.726 ± 0.020,P =0.001) and ENaC-α (treatment vs.control,0.236 ± 0.021 vs.0.814 ± 0.025,P ＜ 0.001) expressions and serum-and glucocorticoid-inducible kinase 1 phosphorylation (treatment vs.control,0.442 ± 0.024 vs.1.046 ± 0.082,P =0.002),indicating the PI3K signaling pathway was involved in regulating NDRG1 expression induced by LXA4.Conclusion:Our research uncovered a critical role of NDRG 1 in LXA4 alleviation of LPS-induced A549 cell injury through mediating PI3K signaling to restore ENaC expression.