Background

Despite advances in the treatments of diabetic complications, proliferative diabetic retinopathy (PDR) still remains a major cause leading to visual loss, mainly because of the lack of pathological mechanisms and complicated protein expressions in vivo. Current study aimed to investigate the patterns of connexin43 (Cx43) changes and the possible interactions with O-GlcNAcylation in DR.

Methods

Clinical samples of vitreous and fibrovascular membranes were acquired from PDR patients during pars plana vitrectomy. Brown Norway rats were used to build diabetic animal models; to investigate the effects of O-GlcNAcylation on Cx43 expressions, total retinal O-GlcNAcylation was changed by intravitreal injections. Levels of protein expressions were examined by immunofluorescence staining and western blot.

Results

Our results revealed increased Cx43 expressions in a vessel-shape pattern followed by the distribution of glial fibrillary acidic protein (GFAP) in diabetic fibrovascular membranes. Similarly, Cx43 and GFAP expressions were elevated in PDR vitreous and diabetic animal retinas. Retinal O-GlcNAcylation was effectively regulated by intravitreal injections, and the increase of Cx43 and GFAP was significantly suppressed by O-GlcNAcylation inhibition under hyperglycemia conditions.

Conclusions

We systemically proved the changes of Cx43 with different retinal cells, and reported the effective methods to regulate retinal O-GlcNAcylation by intravitreal injections, and clearly illustrated the downregulated effects of O-GlcNAcylation inhibition on Cx43 and GFAP expressions.

General significance:

Targeting connexin43 in glial cells reveals a novel mechanism to understand the formation of diabetic fibrovascular membranes and offers a potential therapeutic strategy to interfere the development of PDR.

中文翻译：

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糖尿病视网膜病变中连接蛋白43的鉴定及其下调O-GlcNAcylation抑制胶质细胞活化

背景

尽管糖尿病并发症的治疗取得了进展，但增殖性糖尿病视网膜病变 (PDR) 仍然是导致视力丧失的主要原因，主要是由于缺乏病理机制和体内复杂的蛋白质表达。目前的研究旨在调查连接蛋白 43 (Cx43) 变化的模式以及与 DR 中 O-GlcNAcylation 的可能相互作用。

方法

玻璃体和纤维血管膜的临床样本是在平部玻璃体切除术期间从 PDR 患者获得的。布朗挪威大鼠被用来建立糖尿病动物模型；为了研究 O-GlcNAcylation 对 Cx43 表达的影响，通过玻璃体内注射改变了总视网膜 O-GlcNAcylation。通过免疫荧光染色和蛋白质印迹检查蛋白质表达水平。

结果

我们的结果显示，血管形状模式中 Cx43 表达增加，随后是神经胶质纤维酸性蛋白 (GFAP) 在糖尿病纤维血管膜中的分布。同样，Cx43 和 GFAP 表达在 PDR 玻璃体和糖尿病动物视网膜中升高。玻璃体内注射有效调节视网膜O-GlcNAcylation，高血糖条件下O-GlcNAcylation抑制显着抑制Cx43和GFAP的增加。

结论

我们系统地证明了 Cx43 对不同视网膜细胞的变化，并报道了通过玻璃体内注射调节视网膜 O-GlcNAcylation 的有效方法，并清楚地说明了 O-GlcNAcylation 抑制对 Cx43 和 GFAP 表达的下调作用。

一般意义：

靶向神经胶质细胞中的连接蛋白 43 揭示了一种了解糖尿病纤维血管膜形成的新机制，并提供了一种潜在的治疗策略来干扰 PDR 的发展。