High glucose environment induces NEDD4 deficiency that impairs angiogenesis and diabetic wound healing.

Background: Healing of diabetic wounds, characterized by impaired angiogenesis, remains a clinical challenge. E3 ligase have been identified as potential therapeutic targets of wound healing.

Objective: We assessed the role of E3 ligase NEDD4 in the context of angiogenesis and diabetic wound healing.

Methods: The mRNA expression levels of NEDD4, TSP1 and VEGF were determined by real-time PCR. Western blotting was used to evaluate the protein expression of NEDD4, TSP1 and VEGF. The ubiquitination of TSP1 was evaluated by immunoprecipitation. MTT assay, wound healing assay and tube formation assay were performed to assess the proliferation, migration and angiogenic functions of endothelial cells. The epigenetic modification in the promoter of NEDD4 was confirmed using BSP assay and ChIP-qPCR assay. The role of NEDD4 in wound healing was further verified in diabetic mouse model.

Results: NEDD4 promotes proliferation, migration and tube formation of endothelial cells. It binds to and ubiquitinates TSP1, which lead to TSP1 degradation and thus increased VEGF expression. The inhibitory effect of NEDD4 silencing on the angiogenesis ability of endothelial cells can be restored by TSP1 knockdown. NEDD4 is reduced in diabetic patients, which may due to hypermethylation of NEDD4 promoter mediated via DNMT1 under high glucose condition. Furthermore, inhibition of NEDD4 represses wound healing in diabetic mouse model.

Conclusion: NEDD4 might promote angiogenesis and wound healing by inhibiting TSP1 via ubiquitination in diabetic patients.