NSUN3-mediated m⁵C modification of TAK1 promotes sepsis-induced pulmonary injury through regulating inflammation

Sepsis-induced pulmonary injury (SPI) is a life-threatening condition with high mortality. This study aimed to investigate the role of NOP2/Sun RNA methyltransferase 3 (NSUN3) in SPI and its underlying mechanisms.

Bioinformatics analysis of the GSE10474 dataset revealed differentially expressed genes in acute lung injury. A cecum ligation and puncture (CLP) rat model was established. Lung injury was evaluated via hematoxylin and eosin (H&E) staining. Enzyme-linked immunosorbent assay (ELISA) and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) were used to detect inflammatory cytokine mRNA expression and protein levels. In vitro, human lung microvascular endothelial cells (HULEC-5a) were treated with lipopolysaccharide and transfected with NSUN3-silencing or TAK1-overexpression vectors. Methylated RNA immunoprecipitation (MeRIP) and dual-luciferase assays were conducted to investigate the interactions between NSUN3 and transforming growth factor β-activated kinase 1 (TAK1).

NSUN3 expression was upregulated in CLP-induced rat lung tissues and LPS-stimulated HULEC-5a cells. NSUN3 inhibition attenuated lung injury and decreased inflammatory cytokine levels in both models. Mechanistically, NSUN3-mediated m⁵C modification enhanced TAK1 mRNA stability in HULEC-5a cells. TAK1 overexpression counteracted the anti-inflammatory effects induced by NSUN3 knockdown.

NSUN3-mediated m⁵C modification of TAK1 promoted SPI through regulating inflammation, providing a new insight for SPI treatment.