研究RAD21突变在角膜巩膜化病的致病机理

巩膜化角膜病是角膜发生异常导致角膜不透明。目前角膜移植是恢复视力的唯一治疗方法。为了开发替代治疗，需要了解角膜巩膜化病的发病机制。最近我们找到一个角膜巩膜化家系。19个家系成员中6位病人被确诊为巩膜化角膜病。全基因组测序发现基因RAD21 1348位碱基杂合突变。未患病成员中，RAD21 1348每个DNA拷贝都是胞嘧啶。在患者中碱基为胞嘧啶和胸腺嘧啶，导致蛋白在450处的半胱氨酸被精氨酸取代，造成非同义突变。此RAD21突变是首次于角膜巩膜化病中发现，并在家系三代成员多个患者中遗传。RAD21在有丝分裂和基因转录调节中有重要作用。本项目将从家系成员取得淋巴细胞来研究RAD21杂合突变在有丝分裂和基因转录调节的影响。此外将注射rad21突变型mRNA到非洲爪蟾，以研究rad21 突变在早期胚胎发育的影响。这项研究将提高我们对这种潜在致盲眼病发病机理的认识，结果将有助于治疗手段的发展。

Sclerocornea is an abnormality of opacity at the peripheral part or the entire surface of a cornea. Those patients with sclerocornea affecting the whole corneal surface area usually suffer complete blindness. And those with peripheral sclerocornea would still have visual field restriction. Currently there is no medication to treat sclerocornea. Corneal transplantation is the only treatment to restore vision. Given the limited supply of cornea for transplantation, there is a need to understand the disease mechanism of sclerocornea for the development of alternative treatments..Recently we identified a mutation in the RAD21 gene in a Chinese family showing peripheral sclerocornea-like characteristics in six individuals over three generations out of nineteen family members. Apart from the sclerocornea-like characteristics, the affected members also have thinner central cornea. We found all affected members share the same heterozygous R450C mutation in RAD21. Codon 450 is important for RAD21 functions in cell division and transcription regulation. According to our knowledge, R450C is the first reported RAD21 mutation in sclerocornea inherited in multiple affected family members..RAD21 is a key protein to ensure faithful DNA separation in cell division. Also RAD21 is important in gene transcription regulation. Our preliminary data has established the association of RAD21 in sclerocornea. Therefore we aim to study the biological impact of R450C in RAD21. White blood cells from the affected family members carrying the specific RAD21 mutation will be isolated. And white blood cells from unaffected family members and from people unrelated to this family will also be isolated. Both the white blood cells and the corneal cells will be used to study the consequences of the RAD21 mutation by measuring any defects in cell division and gene transcription. In addition, the wild-type and mutated rad21 will be injected into frog embryos to study the eye development and gene transcription regulation. This study will advance our understanding about the roles of RAD21 in sclerocornea.