YY1 lactylation promotes fibroblast senescence by targeting the PU.1-BTG2 axis to promote oral submucous fibrosis

Oral submucous fibrosis (OSF) is a chronic fibrotic disease common in Asia-Pacific regions and strongly linked to long-term areca nut chewing. Fibroblast senescence is known to contribute to tissue fibrosis, but the molecular mechanisms behind it remain unclear. In this study, we explored how arecoline, a key component of areca nut, influences fibroblast behavior. Specifically, human oral fibroblasts were treated with 100 μM arecoline, which significantly increased the expression of the transcription factor PU.1(Purine-rich box 1) (∼3.5-fold mRNA, ∼3-fold protein). Notably, overexpression of PU.1 (encoded by SPI1) enhanced collagen production, while its inhibition reduced fibrotic markers. To further investigate, RNA sequencing and bioinformatics analysis identified BTG2 (B-cell Translocation Gene 2) as a downstream target of PU.1. Moreover, ChIP-qPCR confirmed PU.1 binding to the BTG2 promoter. Further assays, including western blotting, immunofluorescence, and SA-β-gal staining, showed that the PU.1-BTG2 axis promoted fibroblast senescence and collagen accumulation. Moreover, further analysis revealed that arecoline-treated fibroblasts produced more lactate, which led to increased lactylation of the transcription factor YY1(Yin Yang 1). Interestingly, YY1 was found to enhance PU.1-BTG2 transcription and drive fibrotic responses. Critically, mutation of YY1 at lysine 183 blocked its lactylation and eliminated its ability to activate PU.1 and BTG2. Finally, an arecoline-exposed OSF mouse model validated key in vivo aspects of this pathway, supporting its physiological relevance. Overall, we demonstrate that lactylated YY1 promotes fibroblast senescence and collagen deposition by activating the PU.1-BTG2 axis. This newly identified mechanism highlights potential therapeutic targets for treating OSF.