| 目的：白内障是国内外第一位致盲性眼病，因其发病机制复杂，至今尚未明确。近年来研究表明基因表达异常与白内障的发生密切相关。晶状体上皮细胞特异性基因表达可能对于晶状体上皮细胞的生长、分化或细胞损伤修复这些特殊过程起了关键的作用。1995年~2001年Yi Wen教授发现一种晶状体上皮细胞特异表达的基因LEP503 (lens epithelium gene product 503, LEP503)。研究表明LEP503在正常人晶状体和培养的晶状体上皮细胞系中表达，并且与分化有关，然而LEP503在白内障患者中是否表达以及是否与增殖有关，目前还未有报道。本实验旨在研究LEP503在不同年龄白内障患者以及正常人晶状体中表达情况，探讨白内障发生机制。
方法：收集2003年3月~6月不同年龄白内障患者术中取下的晶状体前囊膜，年龄从7~90岁不等；2003年~2004年无白内障发生的尸体眼的晶状体前囊膜，年龄从10~91岁不等。从中选出50岁以下白内障患者10例（设为白内障中青年组）、50岁以上白内障患者10例（设为白内障老年组）、无白内障的正常人15例（设为正常对照组）。各组标本均男女混合，比例均为1:1，以排除性别差异影响。通过RT-PCR和Western-Blotting技术检测各组LEP503基因和蛋白表达情况，凝胶成像分析系统测定电泳条带密度值（根据IOD密度值和Marker含量换算出样品的DNA含量，再与内参基因β-actin的DNA含量相比，进行标准化），来比较各组之间LEP503表达的差异。利用SPSS12.0软件包，t检验和线性回归进行统计学分析。
结果：1.RT-PCR和凝胶成像分析结果显示：正常对照组和白内障组年龄指标均衡，可比性好，其中白内障组LEP503基因表达比正常对照组高，两者比较有显著性差异P＜0.01；白内障中青年组和老年组之间LEP503基因表达有显著性差异P＜0.01；而正常人中青年和老年之间LEP503基因表达无显著性差异，P=0.75；白内障患者LEP503表达量与年龄之间呈明显的线性关系，P<0.01，其随着年龄的增加表达增高。2.Western-Blotting结果显示：白内障患者LEP503蛋白表达量明显比正常人高，且年龄越大LEP503蛋白表达越强，与RT-PCR结论一致，而正常人LEP503蛋白表达未见明显规律。
结论：1. LEP503基因在白内障患者中有表达且比正常人高；2. 白内障患者LEP503基因的表达量与患者年龄之间呈线性关系。3. LEP503基因与晶状体上皮细胞增殖没有直接关系；4. LEP503基因可能参与了老年人白内障和中青年人白内障不同发病机制过程。
Abstract
Objective: It is known that cataract is the worldwide principal blindness-incurring disease, but the pathogenesis remains unclear because of its complication so far. Studies in recent years by professor Yi Wen showed that the occurrence of cataract had close relationship with disorder of gene expression. The genes specifically expressed in lens epithelial cells may play a key role in the process of growth, differentiation and repair of injuries in lens epithelium. It is not reported that the exclusive gene of lens epithelial cells, LEP503 (lens epithelium gene product 503, LEP503), either is expressed in cataract patients, or has involved in proliferation in patients’ lens epithelial cells, while LEP503 is expressed in normal lens epithelium or LECs in culture according to the investigation reports. Aiming at discussion of the mechanism of cataract by investigating the expression of LEP503 gene, which is specifically expressed in lens epithelial cells, in different age of cataract patients and normal persons.
Methods: Anterior capsular membranes of lens from different age of cataract patients were divided into two groups, the youth group (under 50years) and the senile group (above 50years), and the anterior capsular membranes of lens of corpse without cataract were collected to be control group. The proportion between male and female in each of groups was 1:1 so as to exclude the effects of gender. The expression of LEP503 gene was detected by RT-PCR, LEP503 protein by Western-Blotting, and electrophoresis strap’s density aiming at comparing the difference of LEP503 expression between cataract group and control group by Gel Imaging Assay system. Data was analyzed by T test and linear regression statistically with SPSS12.0.
Results: 1.RT-PCR showed good balance of age in the cataract group and control group, and the parameters are comparable. All the samples expressed LEP503 gene, and the expression level in cataract group was higher than that of control group. There was significant difference between cataract patients and normal persons P＜0.01, and between cataract patients in youth group and senile group as well, but not in control group P=0.75. There is a linear relationship between the expressing level of LEP503 and patient’s age. 2.Western-Blotting showed the protein expression level of LEP503 was more notable in cataract group than in control group, and the level increasing in cataract group accorded with the rising of patient’s age, whereas there is no obvious rules of LEP503 expression among the control group.
Conclusion: 1.Cataract patients express LEP503 and the expression level is higher than that of normal persons. 2.There is a linear relationship between the expressing level of LEP503 and cataract patient’s age. 3.There is no direct relationship between the expression of LEP503 and the proliferation of lens epithelial cells. 4.LEP503 may play different roles in the pathogenesis of senile and youth cataract. |
