Department of Pathology, The University of Western Ontario, London, Ontario, Canada.
Diabetes. 2011 Apr;60(4):1314-23. doi: 10.2337/db10-1557. Epub 2011 Feb 28.
Diabetic retinopathy (DR) is a leading cause of blindness. Increased vascular endothelial growth factor (VEGF), promoting angiogenesis and increased permeability, is a key mechanistic abnormality in DR. We investigated microRNA (miRNA) alterations in DR with specific focus on miR-200b, and its downstream target, VEGF.
miRNA expression profiling microarray was used to examine the retinas of streptozotocin-induced diabetic rats. Expressions of specific miRNAs were verified with PCR in the rat retina and in glucose-exposed endothelial cells. A target search, based on sequence complementarities, identified specific targets. We analyzed mRNA levels and protein expression in endothelial cells from large vessels and retinal capillaries and in the rat retina, with or without injection of miR-200b mimic or antagomir. Localization of miR-200b and its functional analysis in the rat and human retinas were performed.
Alteration of several miRNAs, including downregulation of miR-200b, were observed in the retina in diabetes. Such downregulation was validated in the retina of diabetic rats and in endothelial cells incubated in glucose. In parallel, VEGF (target of miR-200b) mRNA and protein were elevated. In the retina, miR-200b was localized in neuronal, glial, and vascular elements. Transfection of endothelial cells and intravitreal injection of miR-200b mimic prevented diabetes-induced increased VEGF mRNA and protein. Also prevented were glucose-induced increased permeability and angiogenesis. Furthermore, transfection of miR-200b antagonists (antagomir) led to increased VEGF production. Similar alterations were seen in the human retina.
These studies show a novel mechanism involving miR-200b in DR. Identification of such mechanisms may lead to the development of novel miRNA-based therapy.
糖尿病性视网膜病变（DR）是失明的主要原因。血管内皮生长因子（VEGF）的增加，促进血管生成和通透性增加，是 DR 的关键机制异常。我们研究了 DR 中的 microRNA（miRNA）变化，特别关注 miR-200b 及其下游靶标 VEGF。
使用 miRNA 表达谱微阵列检查链脲佐菌素诱导的糖尿病大鼠的视网膜。在大鼠视网膜和葡萄糖暴露的内皮细胞中，通过 PCR 验证特定 miRNA 的表达。基于序列互补性的靶搜索确定了特定的靶标。我们分析了大血管和视网膜毛细血管内皮细胞以及糖尿病大鼠视网膜中 mRNA 水平和蛋白表达，同时注射 miR-200b 模拟物或 antagomir。在大鼠和人视网膜中进行了 miR-200b 的定位和功能分析。
在糖尿病中观察到几种 miRNA 的改变，包括 miR-200b 的下调。这种下调在糖尿病大鼠的视网膜和葡萄糖孵育的内皮细胞中得到了验证。同时，VEGF（miR-200b 的靶标）mRNA 和蛋白升高。在视网膜中，miR-200b 定位于神经元、神经胶质和血管成分。转染内皮细胞和玻璃体腔注射 miR-200b 模拟物可防止糖尿病诱导的 VEGF mRNA 和蛋白增加。还可防止葡萄糖诱导的通透性增加和血管生成。此外，转染 miR-200b 拮抗剂（antagomir）可导致 VEGF 产生增加。在人视网膜中也观察到类似的改变。
这些研究显示了 DR 中涉及 miR-200b 的新机制。鉴定此类机制可能会导致开发新的基于 miRNA 的治疗方法。
