P300 Promotes RUNX1 Transcription to Regulate Autophagy and Drive Corneal Neovascularization.

Purpose: This study aimed to elucidate the regulatory role of Runt-related transcription factor 1 (RUNX1) in corneal neovascularization (CoNV) and its possible mechanisms.

Methods: In VEGF-induced human umbilical vein endothelial cells (HUVECs), lentiviral vectors were used to knock down or overexpress RUNX1, and plasmid transfection was employed to knock down P300. EdU assay, Transwell assay, and tube formation assay were conducted to assess cell proliferation, migration, and tube formation ability, respectively. Chromatin immunoprecipitation, followed by quantitative PCR, was performed to verify the binding of P300 and RUNX1. Co-immunoprecipitation was carried out to detect the formation of the RUNX1-P62 complex. Autophagic flux was monitored by using RFP-GFP-LC3 tandem fluorescence reporters. For in vivo validation, a rat model of corneal neovascularization was established by alkali burn induction. The expression of RUNX1 was verified by quantitative real-time PCR and Western blotting. Short hairpin RNA targeting RUNX1 was injected subconjunctivally into alkali-burned rats, and the area of corneal neovascularization and pathological changes were observed. Western blotting and immunofluorescence were used to detect the expression of relevant proteins.

Results: The results showed that in the context of CoNV and VEGF-induced HUVECs, the autophagy signaling pathway is inhibited, while the levels of RUNX1 and P300 are significantly increased. Overexpression of RUNX1 reverses the inhibitory effect of P300 silencing on angiogenesis. P300 binds to a specific regulatory element in the RUNX1 promoter, thereby facilitating RUNX1 transcription. Notably, silencing RUNX1 can attenuate the stimulatory effects of VEGF on the proliferation, migration, and tube formation of HUVECs by activating autophagy.

Conclusions: P300 binds to the RUNX1 promoter to enhance its transcription, and RUNX1 subsequently regulates autophagy-related genes to influence CoNV progression.