O-GlcNAc糖基化修饰在糖尿病性白内障中的作用

Role of O-GlcNAc glycosylation in diabetic cataract

目的:分析O-连接N-乙酰氨基葡萄糖(O-GlcNAc)修饰在年龄相关性白内障和糖尿病性白内障晶状体前囊膜中的表达变化,探讨O-GlcNAc糖基化修饰在糖尿病性白内障中的作用。方法:以糖尿病性白内障患者54例56眼和年龄相关性白内障患者115例120眼的晶状体前囊膜为研究对象,利用免疫印迹技术检测年龄相关性和糖尿病性白内障晶状体前囊膜中O-GlcNAc蛋白的表达水平,富集晶状体前囊膜组织中O-GlcNAc糖蛋白并通过质谱方法鉴定两组样本晶状体前囊膜中O-GlcNAc差异蛋白的表达。结果:免疫印迹结果显示,糖尿病性白内障组晶状体前囊膜中O-GlcNAc蛋白表达水平显著高于年龄相关性白内障组(P<0.01),且随着糖化血红蛋白水平的升高,O-GlcNAc蛋白表达水平也升高(P<0.01)。我们采用质谱法对糖尿病性白内障和年龄相关性白内障晶状体前囊膜中O-GlcNAc蛋白进行差异分析,在糖尿病性白内障组中发现5种表达上调的O-GlcNAc蛋白(FABP5、KRT16、PGK1、CTSD、S100A7),18种表达下调的O-GlcNAc蛋白(CRYβB1等),同时我们还鉴定出3个新的O-GlcNAc糖基化修饰位点:蛋白质PTPRQ的T1730和S1738位的O-GlcNAc糖基化和蛋白质ATP5MC2的T61位的O-GlcNAc糖基化。结论:O-GlcNAc糖基化修饰可能参与了糖尿病性白内障的形成和发展。质谱鉴定出的O-GlcNAc差异蛋白为进一步研究糖尿病性白内障的发病机制提供了理论依据。

AIM:To analyze the expression changes of O-linked N-acetylglucosamine(O-GlcNAc)glycoprotein in the lens capsule of age-related cataract and diabetic cataract and investigate the role of O-GlcNAc glycoprotein in diabetic cataract.METHODS:The lens capsules of 54 patients(56 eyes)with diabetic cataract and 115 patients(120 eyes)with age-related cataract were studied.Immunoblotting was used to detect the expression level of O-GlcNAc protein in the lens capsules of age-related and diabetic cataracts,and mass spectrometry was used to identify the O-GlcNAc glycoproteins in lens capsules.RESULTS:Immunoblotting results showed that the expression level of O-GlcNAc protein in the lens capsule of diabetic cataracts was significantly higher than in the age-related cataracts(P<0.01).With the level of glycosylated hemoglobin increasing,the expression level of O-GlcNAc protein also increased(P<0.01).Totally 5 O-GlcNAc proteins with up-regulated expression(FABP5,KRT16,PGK1,CTSD and S100A7),and 18 O-GlcNAc proteins with down-regulated expression(CRYβB1,etc.)were identified in the lens capsule of patients with diabetic cataract by mass spectrometry.Three new O-GlcNAc glycosylation sites were identified in this study.They were O-GlcNAcylation at T1730 position and S1738 position of PTPRQ and O-GlcNAcylation at T61 position of ATP5MC2.CONCLUSION:O-GlcNAc glycosylation may be involved in the formation and development of diabetic cataract.The differential O-GlcNAc glycoprotein identified by mass spectrometry provided the data for further study about pathogenesis of diabetic cataract.