Kresge Eye Institute, Wayne State University, Detroit, Michigan, United States.
Invest Ophthalmol Vis Sci. 2014 Jun 3;55(9):5653-60. doi: 10.1167/iovs.14-14383.
In the pathogenesis of diabetic retinopathy, matrix metalloproteinase (MMP)-9 damages retinal mitochondria, activating the apoptotic machinery. Transcription of MMP-9 is regulated by nuclear factor kappa B (NF-κB), and the activation of NF-κB is modulated by the acetylation of its p65 subunit. Sirtuin 1 (Sirt1), a deacetylase, plays an important role in the acetylation-deacetylation of p65. The goal of this study is to investigate the role of Sirt1 in the activation of MMP-9 in diabetic retinopathy.
The effect of hyperglycemia and Sirt1 activator, resveratrol, on acetylation of p65 and its binding at MMP-9 promoter-and mitochondrial damage and apoptosis-was assessed in the retinal endothelial cells. Role of oxidative stress in the regulation of Sirt1 was evaluated in the cells incubated in H2O2. The results were confirmed in the retina from diabetic mice with Sod2 or MMP-9 gene manipulated.
High glucose decreased Sirt1 activity and increased p65 acetylation, and resveratrol prevented increase in p65 acetylation, binding of p65 at MMP-9 promoter and MMP-9 activation, mitochondria damage, and cell apoptosis. While Sirt1 was decreased by H2O2, MMP-9 was significantly increased. Retina from wild-type diabetic mice presented similar decrease in Sirt1, and diabetic mice with Sod2 overexpression or MMP-9 deletion had normal retinal Sirt1. Retinal microvasculature from human donors with established diabetic retinopathy also had decreased Sirt1.
Thus, in diabetes, increase in oxidative stress inhibits Sirt1 and p65 is hyperacetylated, increasing the binding of p65 at MMP-9 promoter. Prevention of Sirt1 inhibition, via modulating acetylation of p65, should protect activation of MMP-9 and inhibit the development of diabetic retinopathy.
在糖尿病性视网膜病变的发病机制中，基质金属蛋白酶（MMP）-9 损害视网膜线粒体，激活凋亡机制。MMP-9 的转录受核因子κB（NF-κB）调控，NF-κB 的激活受其 p65 亚基乙酰化的调节。去乙酰化酶 Sirtuin 1（Sirt1）在 p65 的乙酰化-去乙酰化中发挥重要作用。本研究旨在探讨 Sirt1 在糖尿病性视网膜病变中 MMP-9 激活中的作用。
在视网膜内皮细胞中，评估高血糖和 Sirt1 激活剂白藜芦醇对 p65 乙酰化及其在 MMP-9 启动子上的结合以及线粒体损伤和细胞凋亡的影响。在孵育于 H2O2 的细胞中评估氧化应激对 Sirt1 调节的作用。在 Sod2 或 MMP-9 基因操作的糖尿病小鼠的视网膜中证实了这些结果。
高葡萄糖降低 Sirt1 活性并增加 p65 乙酰化，而白藜芦醇可防止 p65 乙酰化增加、p65 与 MMP-9 启动子结合以及 MMP-9 激活、线粒体损伤和细胞凋亡。虽然 H2O2 降低了 Sirt1，但 MMP-9 明显增加。野生型糖尿病小鼠的视网膜 Sirt1 也减少，而过表达 Sod2 或缺失 MMP-9 的糖尿病小鼠的视网膜 Sirt1 正常。来自已确诊糖尿病性视网膜病变的人类供体的视网膜微血管也存在 Sirt1 减少。
因此，在糖尿病中，氧化应激增加抑制 Sirt1，p65 发生过度乙酰化，增加 p65 在 MMP-9 启动子上的结合。通过调节 p65 的乙酰化来防止 Sirt1 抑制，应该可以保护 MMP-9 的激活并抑制糖尿病性视网膜病变的发展。
