ABSTRACT

Aim

To explore the role of microRNA-26a-5p (miR-26a) in early diabetic retinal neuronal cell death and reveal the underlying mechanism(s).

Methods

A streptozotocin (STZ)-induced diabetic mouse model was established using C57BL/6 J mice. Control or miR-26a mimic was intravitreally injected. Hematoxylin-eosin (H&E) and transmission electron microscopy (TEM) were used to observe the morphologic alterations in the retinal structure and ultrastructure, respectively. The expression of miR-26a and phosphatase and tensin homolog (PTEN) was assayed using qRT-PCR and western blotting, respectively. An immunofluorescence assay was used to investigate the distribution of PTEN expression in the retina. The expression of glial fibrillary acidic protein (GFAP) was measured to identify glial cell activation. The mRNA levels of IL-1β, NF-κB, and VEGF were examined to assess diabetic retinal inflammation.

Results

miR-26a expression was decreased in retinal tissues of diabetic mice, and injection of miR-26a mimic restored the miR-26a level. Diabetic mice had significantly reduced neuroretinal thickness and ganglion cell number; miR-26a mimic delayed the thinning of neuroretinal layers and the loss of ganglion numbers. TEM showed damaged ultrastructure of retinal ganglions in diabetic mice, while miR-26a mitigated the damages. PTEN expression was increased mainly in the inner and outer nuclear layer of the retina in diabetic mice; miR-26a mimics lowered PTEN expression. GFAP, IL-1β, NF-κB, and VEGF expression were significantly increased in the diabetic mice, and intravitreal delivery of miR-26a resulted in a down-regulated expression of these factors.

Conclusion

miR-26a can protect against retinal neuronal impairment in diabetic mice by down-regulating PTEN, highlighting the potential of miR-26a as a target for DR treatment.

中文翻译：

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microRNA-26a-5p 通过靶向 PTEN 预防糖尿病小鼠视网膜神经元细胞死亡

摘要

目标

探讨 microRNA-26a-5p (miR-26a) 在早期糖尿病视网膜神经元细胞死亡中的作用并揭示其潜在机制。

方法

使用 C57BL/6 J 小鼠建立了链脲佐菌素 (STZ) 诱导的糖尿病小鼠模型。玻璃体内注射对照或 miR-26a 模拟物。苏木精-伊红 (H&E) 和透射电子显微镜 (TEM) 分别用于观察视网膜结构和超微结构的形态学变化。分别使用 qRT-PCR 和蛋白质印迹测定 miR-26a 和磷酸酶和张力蛋白同源物 (PTEN) 的表达。免疫荧光测定用于研究视网膜中 PTEN 表达的分布。测量胶质纤维酸性蛋白 (GFAP) 的表达以识别胶质细胞活化。检查 IL-1β、NF-κB 和 VEGF 的 mRNA 水平以评估糖尿病视网膜炎症。

结果

糖尿病小鼠视网膜组织中 miR-26a 表达降低，注射 miR-26a 模拟物可恢复 miR-26a 水平。糖尿病小鼠的神经视网膜厚度和神经节细胞数量显着减少；miR-26a 模拟物延迟了神经视网膜层的变薄和神经节数量的减少。TEM显示糖尿病小鼠视网膜神经节超微结构受损，而miR-26a减轻了损伤。PTEN表达增加主要在糖尿病小鼠视网膜的内核层和外核层；miR-26a 模拟降低的 PTEN 表达。糖尿病小鼠中 GFAP、IL-1β、NF-κB 和 VEGF 的表达显着增加，而 miR-26a 的玻璃体内递送导致这些因子的表达下调。

结论

miR-26a 可以通过下调 PTEN 来保护糖尿病小鼠免受视网膜神经元损伤，突出了 miR-26a 作为 DR 治疗靶点的潜力。