晶状体的老化和白内障形成

1、晶状体的老化和白内障形成【关键词】 白内障 Ageing lens and development of cataract 【Abstract】 The structural changes of the ageing lens include the increase of lens mass and lens density, the thickening of the anterior lens capsule and the decrease in density of epithelium. The accumulation of fluorogen may play a major

2、 role in the yellowing and increasing fluorescence of the lens with age. Increased posttranslational modification of proteins and unfolding of proteins eventually result in the aggregation of proteins and the inactivation of enzymes. The powerful antioxidant scavengers and chaperone molecules of len

3、s are minimized during ageing, thus aggravating the damage induced by posttranslational modification. Cataract, the final stage of the ageing lens, may be regarded as a signal of ageing in other organs. Molecular chaperone may r和蛋白质蛋白质二硫化合物较少1.可能是由于良好的氧化防御系统的存在和非常低的氧应激有关.Truscott36认为随着老化，晶状体中存在一种被称为

4、“屏障”的结构产生，主要抑制晶状体内代谢物的传输.这种“屏障结构”可导致一些有害的代谢产物滞留，并增加其存活的半衰期，比如紫外线过滤因子，这进一步增加了晶状体核蛋白质翻译后的修饰机会；同时屏障结构也可抑制抗氧化剂在晶状体中的流动，即使晶状体上皮细胞和皮质功能尚好，氧化作用也可能会在晶状体核区域发生. 5展望 老化和一些年龄相关性疾病中，均存在蛋白质的翻译后修饰，蛋白质去折叠，最终导致蛋白质凝聚，这被称为构象性疾病37.这组疾病有类似的病因，既均与老化相关.它包括淀粉病（Alzheimer病、全身淀粉样变性、Down综合征等）、朊病毒病(CJD vCJD BSE，Kuru) 、Huntingto

5、n病、Alexander病和白内障.相同的病因，类似的发病机制，很可能存在相同的治疗方法.例如，因为谷胱甘肽(GSH)在各种白内障中均降低，提高晶状体中的GSH已被用于治疗白内障.同样提高GSH也已成为年龄相关性神经变性疾病Alzheimer病的治疗策略38.阿斯匹林类药物治疗Alzheimer病、白内障、心肌缺血、中风和各种肿瘤的临床资料也有力的支持了这种推测14. 英国牛津大学眼科的最新研究成果显示晶体蛋白和含巯基的还原剂共同作用，可使人白内障晶状体中活性已丧失的酶起死回生27.晶状体蛋白和硫甲丙脯酸使谷胱甘肽还原酶活性回升79%，晶状体蛋白和二硫苏糖醇使巯醇转移酶活性增加200%.这进一

6、步揭示了晶体蛋白的分子伴侣活性在维持晶状体代谢中的重要性，同时也为白内障的治疗提供了全新的思路.分子伴侣可解救一类由于蛋白质错误折叠累积导致的构象性疾病，首次临床应用药物性伴侣治疗构象性疾病已取得可喜结果40.我们期待着白内障药物治疗研究的突破. 【参考文献】 1 Harding JJ. Cataract: Biochemistry, Epidemiology and Pharmacology M. London, Chapwan and hall,1991:25-134. 2 West SK, Munoz B, Istre J, et al. Mixed lens opacities and

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