ESTABLISHMENT OF AN ANIMAL MODEL FOR CONGENITAL CRANIOFACIAL DISEASES BY GENE TARGETING AND DEVELOPMENT OF THEIR GENETIC DIAGNOSIS.

在本研究中，我们通过基因靶向建立ET-1敲除小鼠并对其进行分析，阐明了ET-1新的发育作用及其与人类颅面先天性疾病的潜在关联。ET-1基因敲除小鼠不仅表现出颅面异常，而且还表现出相关的心血管异常（大血管畸形+室间隔缺损），类似于人类先天性疾病，如CATCH22和velo-cardio-facial综合征。这些发现提示ET-1敲除小鼠可能是一种有用的疾病模型。我们推测ET-1可能是神经嵴细胞发育过程中上皮-间质相互作用的中介，而神经嵴细胞在咽弓和心血管系统的形成中起着重要作用。我们还确定了ET-1通路下游的一个候选基因，包括ET-1在内的基因在咽弓和心血管发育中的相互作用将是我们未来研究的下一个主题之一。关于临床意义和新诊断方法的发展，我们发现了人类ET-1基因外显子的多态性。通过使用这种多态性，我们现在正在研究ET-1基因与人类先天性疾病之间的联系，包括皮埃尔-罗宾综合征、特杰-柯林斯综合征和先天性心脏病。此外，我们还成功建立了利用ET-1基因启动子区的血管选择性基因表达系统，并利用该系统成功构建了ET-1过表达小鼠。对ET-1敲除小鼠和ET-1过表达小鼠的系统分析有望进一步阐明ET-1的病理生理作用。

In the present study, we have clarified the novel developmental role of ET-1 and its potential association with human craniofacial congenital diseases through the establishment of ET-1 knockout mice by gene targeting and their analysis. ET-1 knockout mice demonstrated not only craniofacial abnormalities but also associated cardiovascular anomalies (great vessel malformations + ventricular septal defect), which resemble human congenital diseases such as CATCH22 and velo-cardio-facial syndrome. These findings suggest that ET-1 knockout mice may be a useful disease model. We hypothesized that ET-1 may serve as mediator of the epithelial-mesenchymal interaction in the development of neural crest cells which plays an important role in the formation of the pharyngeal arches and cardiovascular system. We have also identified one of the candidate genes downstream to the ET-1 pathway and interaction among genes including ET-1 in the pharyngeal arch and cardiovascular development will be one of the next theme of our future research. Concerning the clinical implication and development of new diagnostic methods, we have found a polymorphism in the exon of the human ET-1 gene. By using this polymorphism, we are now examining the linkage between the ET-1 gene and human congenital diseases including Pierre-Robin syndrome, Treacher-Collins syndrome and congenital heart diseases. Furthermore, we have succeeded in establishing the vessel-selective gene expression system using the ET-1 gene promoter region and ET-1 overexpressing mice using this system. Systematic analysis of both ET-1 knockout mice and ET-1-overexpression mice is expected to further elucidate the pathophysiological role of ET-1.