PU.1 aggravates hepatic sinusoidal obstruction syndrome by upregulating PTBP1 and activating the Wnt/β-catenin pathway.

OBJECTIVE: Hepatic sinusoidal obstruction syndrome (HSOS) is a disease characterized by damage to hepatic sinusoidal endothelial cells (HSECs). This research investigates the role and regulatory pathway of PU box-binding protein (PU.1) in the progression of HSOS. METHODS: HSOS model. PU.1 knockdown was achieved using lentiviral shRNA constructs, and its impact on oxidative stress, PTBP1 expression, β-catenin mRNA stability, and Wnt/β-catenin signaling was evaluated through kits, RT-qPCR, and western blot. Dual-luciferase and chromatin immunoprecipitation assays were conducted to assess the interaction between PU.1 and the PTBP1 promoter. The molecular association between PTBP1 and β-catenin mRNA was confirmed through RNA pull-down and RIP assays. RESULTS: PU.1 was upregulated in MCT-induced HSOS, contributing to elevated oxidative stress and activation of the Wnt/β-catenin pathway. PU.1 directly enhanced PTBP1 transcription, which stabilized β-catenin mRNA and sustained Wnt/β-catenin signaling. PU.1 knockdown alleviated oxidative stress, reduced liver damage, and disrupted the PTBP1-β-catenin interaction, leading to Wnt/β-catenin activity inhibition. Overexpression of PTBP1 reversed the protective effects of PU.1 knockdown, reinstating oxidative stress and reactivating Wnt/β-catenin signaling. CONCLUSION: PU.1 facilitated HSOS pathogenesis by promoting the transcriptional activity of PTBP1 and activating the Wnt/β-catenin pathway. Targeting PU.1 can serve as a promising therapeutic strategy for reducing oxidative stress and liver damage in HSOS.