LAUSR

PURPOSE Forkhead box f1 (FoxF1), a transcription factor, was implicated in lung development. However, the molecular mechanism of FoxF1 in lung injury, specifically in injury caused by paraquat (PQ), one of the most frequently used herbicides, is unknown. Accordingly, we performed this study to investigate whether FoxF1 attenuates PQ-induced lung injury and to determine the possible mechanism. METHODS We used PQ-treated Beas-2B cells to measure the expression of FoxF1. Later, ChIP-qPCR was applied to detect the levels of histone acetylation in cells, followed by the validation of the relationship between histone deacetylase-2 (HDAC2) and FoxF1. Subsequently, the correlation between FoxF1 and microRNA (miR)-342 and the downstream mechanism of miR-342 were evaluated by bioinformatics analysis. The apoptosis and the content of reactive oxygen species (ROS) in PQ-treated cells were detected to evaluate the roles of HDAC2, FoxF1 and miR-342 in vitro. Finally, a rat model was developed to evaluate the effects of HDAC2, miR-342 and Krüppel-like factor 5 (KLF5) on PQ-induced lung injury in vivo. RESULTS PQ treatment significantly enhanced FoxF1 promoter deacetylation, thereby inhibiting FoxF1 expression. After inhibition of HDAC2 activity, apoptosis and oxidative stress induced by PQ were significantly reversed. Nevertheless, further inhibition of miR-342 or overexpression of KLF5 promoted apoptosis and oxidative stress induced by PQ, and IκB/NF-κB p65 signaling was significantly activated after PQ treatment. CONCLUSION PQ treatment inhibited miR-342 expression by promoting HDAC2-induced deacetylation of the FoxF1 promoter, thereby promoting KLF5 expression and the IκB/NF-κB p65 signaling activation, and finally exacerbating PQ-induced lung injury in rats.