Liang Li-Fang, Zhao Jia-Qi, Wu Yi-Fei, Chen Hui-Jie, Huang Tian, Lu Xiao-He
Department of Ophthalmology, Zhujiang Hospital, Southern Medical University, Guangzhou 515282, Guangdong Province, China.
World J Diabetes. 2025 Mar 15;16(3):101328. doi: 10.4239/wjd.v16.i3.101328.
Diabetic macular edema (DME) is the most common cause of vision loss in people with diabetes. Tight junction disruption of the retinal pigment epithelium (RPE) cells has been reported to induce DME development. SMAD-specific E3 ubiquitin protein ligase (SMURF) 1 was associated with the tight junctions of cells. However, the mechanism of SMURF1 in the DME process remains unclear.
To investigate the role of SMURF1 in RPE cell tight junction during DME.
ARPE-19 cells treated with high glucose (HG) and desferrioxamine mesylate (DFX) for establishment of the DME cell model. DME mice models were constructed by streptozotocin induction. The trans-epithelial electrical resistance and permeability of RPE cells were analyzed. The expressions of tight junction-related and autophagy-related proteins were determined. The interaction between insulin like growth factor 2 mRNA binding protein 2 (IGF2BP2) and SMURF1 mRNA was verified by RNA immunoprecipitation (RIP). SMURF1 N6-methyladenosine (m6A) level was detected by methylated RIP.
SMURF1 and vascular endothelial growth factor (VEGF) were upregulated in DME. SMURF1 knockdown reduced HG/DFX-induced autophagy, which protected RPE cell tight junctions and ameliorated retinal damage in DME mice. SMURF1 activated the Wnt/β-catenin-VEGF signaling pathway by promoting WNT inhibitory factor (WIF) 1 ubiquitination and degradation. IGF2BP2 upregulated SMURF1 expression in an m6A modification-dependent manner.
M6A-modified SMURF1 promoted WIF1 ubiquitination and degradation, which activated autophagy to inhibit RPE cell tight junctions, ultimately promoting DME progression.
糖尿病性黄斑水肿（DME）是糖尿病患者视力丧失的最常见原因。据报道，视网膜色素上皮（RPE）细胞的紧密连接破坏会诱导DME的发生。SMAD特异性E3泛素蛋白连接酶（SMURF）1与细胞的紧密连接有关。然而，SMURF1在DME过程中的机制仍不清楚。
研究SMURF1在DME期间RPE细胞紧密连接中的作用。
用高糖（HG）和去铁胺甲磺酸盐（DFX）处理ARPE-19细胞以建立DME细胞模型。通过链脲佐菌素诱导构建DME小鼠模型。分析RPE细胞的跨上皮电阻和通透性。测定紧密连接相关蛋白和自噬相关蛋白的表达。通过RNA免疫沉淀（RIP）验证胰岛素样生长因子2 mRNA结合蛋白2（IGF2BP2）与SMURF1 mRNA之间的相互作用。通过甲基化RIP检测SMURF1 N6-甲基腺苷（m6A）水平。
DME中SMURF1和血管内皮生长因子（VEGF）上调。SMURF1敲低减少了HG/DFX诱导的自噬，保护了RPE细胞紧密连接，并改善了DME小鼠的视网膜损伤。SMURF1通过促进WNT抑制因子（WIF）1的泛素化和降解来激活Wnt/β-连环蛋白-VEGF信号通路。IGF2BP2以m6A修饰依赖的方式上调SMURF1表达。
m6A修饰的SMURF1促进WIF1的泛素化和降解，激活自噬以抑制RPE细胞紧密连接，最终促进DME进展。
