βB2-晶状体蛋白W151C突变导致先天性白内障的分子机制研究

Congenital cataract is the major cause of visual impairment and childhood blindness worldwide. Approximately 30% of congenital cataracts are inherited. About half of the mutations which have been identified responsible for congenital cataract are in the crystallins genes. βB2-crystallin is the one of major structural proteins in the lens. The mutation of CRYBB2 which is the code gene of βB2-crystallin can led to severe congenital cataract. However, the exact mechanism of congenital cataract remains unclear. Mutations in genes encoding abnormal proteins have been found to cause endoplasmic reticulum stress (ERS) and subsequent activation of the unfolded protein response. Autophagy-lysosome pathway (ALP) is the main approach for protein aggregateds and damaged organelles elimination in the cells. Therefore, ERS and ALP have been implicated in the pathogenesis of many protein aggregating diseases. In the project, we aim to further explore the mechanisms of congenital cataract caused by the mutation of βB2-crystallin using the W151C knockin mouse model. Histological section, immunofluorescent staining, immunobloting, and real-time quantitative PCR will be used to demonstratethe the roles of ERS and ALP in the congenital cataract progression. In additon, we also investigate whether the destruction of barrier function of lens epithelial cells caused by fibrosis accounts for lens cortex hydrolysis. These findings will provide new targets and evidence for the treatment of congenital cataract.

先天性白内障是全球范围内儿童视力发育障碍和致盲的主要原因之一，约三分之一为遗传性，其中50%以上为编码晶状体结构蛋白的基因突变所致。βB2-晶状体蛋白是晶状体重要的结构蛋白之一，其编码基因CRYBB2突变可导致严重的先天性白内障，但发病机制复杂，目前尚未明确。突变基因表达的异常蛋白堆积可引发内质网应激，而自噬-溶酶体途径是机体清除异常蛋白的主要途径，因此，内质网应激和自噬-溶酶体途径参与了多种蛋白质积聚性疾病的发病机理，是近几年的研究热点。本项目拟在βB2-晶状体蛋白W151C突变导致的小鼠先天性白内障中，应用组织切片、免疫荧光染色、免疫印迹和荧光定量PCR等技术，研究W151C突变引起晶状体蛋白溶解性下降、内质网应激和自噬-溶酶体途径在先天性白内障中的作用及机制，并验证晶状体上皮细胞纤维化引起的屏障功能破坏是导致白内障晚期晶状体被水解的原因，全面阐述先天性白内障发生发展及转归的病理机制。

先天性白内障是全球范围内儿童视力发育障碍和致盲的主要原因之一，约三分之一为遗传性，其中50%以上为编码晶状体结构蛋白的基因突变所致。βB2-晶状体蛋白是晶状体重要的结构蛋白之一，其编码基因CRYBB2突变可导致严重的先天性白内障，但其发病机制复杂，目前尚未明确。内质网应激和自噬-溶酶体途径参与了多种蛋白质积聚性疾病的发病机理，是近几年的研究热点。本研究通过βB2-晶状体蛋白W151C突变导致的小鼠先天性白内障模型，应用高通量全基因组表达谱芯片、组织切片、免疫印迹和荧光定量PCR等技术，发现W151C突变可引起晶状体蛋白溶解性下降、对抗热变性和氧化应激的能力降低。此外，我们还证实了在晶状体浑浊急速进展期，βB2- W151C突变的结构异常蛋白可激发内质网应激和自噬-溶酶体途径，两者介导的蛋白质合成停滞、蛋白质被过度水解是晶状体浑浊急速发展成全白内障的重要分子机制，并验证晶状体上皮细胞纤维化引起的屏障功能破坏是导致白内障晚期晶状体被水解的原因。本研究全面阐述先天性白内障发生发展及转归的病理机制，并为其防治提供新的靶点及科学依据。