ZKSCAN3 mitigates lipopolysaccharide-induced acute lung injury by restraining excessive autophagy via activation of the mTOR pathway

Abstract

Background Acute lung injury (ALI) is a critical condition marked by dysregulated inflammation and autophagic imbalance. Zinc-finger with KRAB and SCAN domains 3 (ZKSCAN3) is a master transcriptional repressor of autophagy, yet its role in ALI pathogenesis remains unclear. The aim of this study is to elucidate the functional role and underlying mechanisms of ZKSCAN3 in ALI. Methods ALI was induced in C57BL/6 mice and A549 alveolar epithelial cells by lipopolysaccharide (LPS). ZKSCAN3 was overexpressed using plasmid transfection to evaluate its therapeutic potential. Lung injury was assessed by histopathology, wet-to-dry ratio (W/D ratio), and inflammatory cytokine levels [tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β, IL-6]. Autophagic activity was evaluated via transmission electron microscopy(TEM), immunofluorescence, and western blotting for LC3-II, Beclin-1, and P62. The involvement of the mTOR pathway was investigated by examining the phosphorylation status of mTOR. Results ZKSCAN3 expression was significantly downregulated in both LPS-induced lung tissues and A549 cells. Overexpression of ZKSCAN3 markedly alleviated LPS-induced pulmonary edema, alveolar damage, and the surge of pro-inflammatory cytokines. Mechanistically, ZKSCAN3 overexpression suppressed excessive autophagic flux, as evidenced by a decreased LC3-II/LC3-I ratio and Beclin-1 expression, and increased accumulation of P62. Furthermore, this protective effect was associated with a notable increase in mTOR phosphorylation, indicating reactivation of the mTOR-autophagy inhibitory axis. Conclusions Our findings reveal that downregulation of ZKSCAN3 contributes to the pathogenesis of LPS-induced ALI. Restoration of ZKSCAN3 exerts a protective effect by reining in excessive autophagy, through activation of the mTOR signaling pathway. This positions the ZKSCAN3-mTOR axis as a potential therapeutic target for ALI.