PFKFB3 nuclear translocation improves diabetic retinopathy by attenuating endothelial cell senescence through...

Endothelial cell (EC) senescence is a key contributor to retinal vascular dysfunction in diabetic retinopathy (DR), yet its molecular mechanisms remain incompletely understood. While PFKFB3 is well recognized for its critical function in modulating EC glycolysis and angiogenesis, its contribution to endothelial senescence in DR has not been elucidated.

Single-cell RNA sequencing was used to profile EC senescence signatures and barrier/tight-junction programs in diabetic retinas. PFKFB3/USP7 abundance and senescence in vivo and in vitro were assessed by Western blotting, SA-β-gal staining, immunofluorescence, and cell-cycle flow cytometry. PFKFB3-USP7 interaction was examined by co-immunoprecipitation, mass spectrometry, and nuclear colocalization. Retinal vascular dysfunction was quantified by Evans blue leakage and PAS-stained retinal trypsin digests.

Single-cell analysis identified EC subclusters enriched for senescence transcripts and simultaneously depleted for barrier/tight-junction pathways in diabetic retinas. Hyperglycemia reduced PFKFB3 and impaired its nuclear entry, leading to prominent cellular senescence in vitro and in vivo, and restoration of PFKFB3 effectively reversed this phenotype. By establishing stable endothelial cell lines expressing PFKFB3 only in the nucleus (NLS mutant) or cytoplasm (K472Q mutant), we revealed that anti-senescent activity required PFKFB3 nuclear localization. Nuclear-localized PFKFB3 interacted with USP7, a critical modulator of the p53 pathway, and regulated the USP7-p53 axis by constraining their coupling, thereby promoting proteasomal degradation of p53. As a downstream effector of PFKFB3, USP7 abrogated the protective effect of PFKFB3, whereas its inhibition attenuated hyperglycemia-induced senescence and mitigated retinal vascular dysfunction.

Our findings highlighted the essential role of nuclear PFKFB3 dysfunction and USP7-p53 axis dysregulation in mediating EC senescence under diabetic stress, suggesting that targeting PFKFB3 nuclear translocation may be a novel therapeutic strategy for the prevention of diabetic retinopathy.