Advanced glycation end products promote diabetic retinopathy through the p65-p300/SMAD4-miR-409-5p-HIF-1α-VEGF signaling pathway

Diabetic retinopathy (DR) is a major complication of diabetes, with advanced glycation end products (AGEs) implicated in its pathogenesis, although the underlying mechanisms remain unclear. This study investigated the role of AGEs in DR using streptozotocin-induced diabetic mice and AGEs-treated human retinal microvascular endothelial cells (hRMECs). ELISA, PAS staining, qRT-PCR, Western blot, and functional assays were conducted to assess molecular and cellular changes. Our results showed that AGEs and VEGF levels were significantly elevated in the retinas and serum of diabetic mice, accompanied by increased retinal neovascularization. Mechanistically, we found that microR-409-5p was found to be upregulated both in diabetic retinas and AGEs-induced hRMECs, where it promoted cellular proliferation, migration, and tube formation. AGEs activated p65 to induce p300 expression, which subsequently interacted with SMAD4 in the nucleus to enhance the transcription of miR-409-5p. Upregulated miR-409-5p in turn induced HIF-1α expression, leading to VEGF upregulation. These findings demonstrated that AGEs contribute to DR progression via the p65-p300/SMAD4-miR-409-5p-HIF-1α-VEGF signaling pathway, identifying miR-409-5p as a potential therapeutic target for DR intervention.