糖尿病视网膜病变（简称“糖网病”、DR）是糖尿病最常见微血管并发症之一，发病原因主要是血-视网膜屏障（BRB）破坏，但机制仍未完全阐明。我们前期研究发现DR中存在O-GlcNAc糖基化的过度修饰，致使血管内皮生长因子（VEGF）表达上调且BRB紧密连接蛋白丢失，这可能与O-GlcNAc促进STAT3磷酸化（pSTAT3）有关。据此我们推测抑制O-GlcNAc通过下调pSTAT3-VEGF通路发挥对BRB的保护作用。本项目拟采用原代内皮细胞及动物模型，结合Co-IP、病毒转染、WB、免疫荧光、视网膜铺片等技术验证STAT3存在O-GlcNAc与磷酸化共修饰，探讨O-GlcNAc对pSTAT3的修饰及调控作用，从而阐明抑制O-GlcNAc下调pSTAT3-VEGF通路保护BRB的分子机制；并通过临床样本进一步验证。该项目将为DR发病提出新的机理，并为探索DR治疗新靶点提供思路。

Diabetic retinopathy (DR) is one of the most common microvascular complications caused by diabetes mellitus，which is closely associated with the breakdown of blood-retinal barrier (BRB), but the mechanism underlying the disease is not well understood. Recently, we observed that it is associated with elevated O-linked β-N-acetyl glucosamine (O-GlcNAc) levels in DR. The augmented O-GlcNAc could cause overexpression of STAT3 phosphorylation, which is related with the increased expression of vascular endothelial growth factor (VEGF) and decreased occludin levels. Therefore, we suppose that inhibition of O-GlcNAc could downregulate pSTAT3-VEGF pathway to protect BRB function. We will use animal models and primary endothelia cells, to confirm that STAT3 are co-modified by O-GlcNAcylation and phosphorylation, to inspect the effects of O-GlcNAc on pSTAT3 expressions, to explore the regulatory mechanism of O-GlcNAc on BRB breakdown via pSTAT3-VEGF pathway by co-immunoprecipitation, virus infection, western blot, immunofluorescence and retinal serial sections. Furtherly, clinical samples will be used to confirm the relationship between the modification levels and BRB function. The study will help to illustrate the pathogenesis of BRB breakdown and provide new insights in the treatment of DR.