ESTABLISHMENT OF MICE DEFICTENT IN A VASOACTIVE PEPTIDE BY GENE TARGETING AND THEIR APPLICATION TO PATHOPHYSIOLOGICAL ANALYSIS

本研究通过基因打靶技术建立ET-1基因敲除小鼠模型并对其进行分析，阐明了ET-1新的发育作用及其在血压调节中的意义。我们推测ET-1可能作为神经嵴细胞发育中上皮-间质相互作用的介质，神经嵴细胞在咽弓和心血管系统的形成中起重要作用。特别是ET-1基因敲除小鼠的表型与人类先天性疾病如CATCH 22和腭心面综合征的表型非常相似，提示ET-1基因敲除小鼠可能为阐明这些疾病的遗传机制和开发新的治疗策略提供线索。在ET-1基因敲除的杂合子中，血压反常地升高，表明ET-1可能不仅仅是作为一种升压剂，ET-1参与心血管稳态的调节是相当复杂的。随后，我们发现在ET-1基因敲除小鼠中，除了血压升高之外，呼吸和应激反应也异常。这些发现揭示了ET-1在中枢心肺调节中的作用。在阐明ET-1的病理生理作用时，建立ET-1基因敲除小鼠的疾病模型具有重要意义。ET-1基因敲除小鼠动脉粥样硬化和高血压等疾病模型的建立正在进行中。此外，我们已经成功地建立了血管选择性基因表达系统使用ET-1基因启动子区和ET-1过表达小鼠使用该系统。对ET-1基因敲除小鼠和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 and the implication in blood pressure regulation of ET-1 through the establishment of ET-1-knockout mice by gene targeting and their analysis. We hypothesized that ET-1 may serve as a 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. Particularly, the phenotype of ET-1 knockout homozyotes (craniofacial abnormalities+great vessel malformations+ventricular septal defect) and human congenital diseases such as CATCH22 and velo-cardio-facial syndrome are very similar, suggesting that ET-1 knockout mice may give a clue to clarification of the genetic mechanism of these diseases and development of new therapeutic strategis. In ET-1 knockout heterozygotes, blood pressure was paradoxically elevated, indicating that ET-1 may not simply act as a pressor and the involvement of ET-1 in the regulation of cardiovascular homeostasis is rather complicated. Subsequently, we have found abnormalities in respiration and response to stress in addition to blood pressure elevation in ET-1 knockout mice. These findings have shed a light on the role of ET-1 in central cardiopulmonary regulation. In the elucidation of the pathophysiological role of ET-1, it would be of great use to make disease models inET-1 knockout mice. Establishment of disease models including atherosclerosis and hypertension in ET-1 knockout mice is in progress. 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 pahophysiological role of ET-1.