Studies on the regulation of biosynthesis of prostacyclin and thromboxane A_2 and search of their new biological activities.

前列环素（PGI_2）和血栓素（TX）A_2是心血管系统中具有强大生物活性的脂质生物因子，与血栓形成、动脉粥样硬化等疾病密切相关。近年来，我们发现PGI_2和TX酶不仅在心血管组织中表达，而且在免疫系统和生殖系统中也有表达。本课题的目的是通过对PGI_2和TXA_2合成酶基因表达机制的分析，阐明PGI_2和TXA_2生物合成的调控机制，并以PGI_2和TXA_2合成酶基因为靶点，寻找新的PGI_2和TXA_2生物活性。在这项研究中，我们发现了以下结果。1. PGI_2合成酶基因启动子分析表明，在内皮细胞或新生内膜血管平滑肌细胞中存在重要的特异性转录启动子区。2.循环应变弱诱导牛内皮细胞PGI_2合酶和环氧合酶-2基因表达，但不诱导环氧合酶-1基因表达。3.建立了PGI_2合成酶基因打靶小鼠模型。小鼠PGI_2完全缺乏，肾脏出现形态学改变。在军团中发现了血管壁增厚、动脉粥样硬化和纤维化。4.用HVJ-脂质体法将人PGI_2合成酶基因导入大鼠颈动脉球囊损伤后，血管壁中PGI_2的生成增加，新生内膜中人PGI_2合成酶的表达增加，并明显抑制新生内膜的形成。5.我们成功地生产TX合酶基因靶向小鼠。

Prostacyclin (PGI_2) and thromboxane (TX) A_2 that are lipid bio-factors with potent biological activities in cardiovascular system are involved in diseases such as thrombosis and atherosclerosis. Recentry, we found that both PGI_2 and TX synthases are expressed not only in cardiovascular tissues but also in tissues of the immune system and reproduction. The purpose of this project is to make clear the regulation of PGI_2 and TXA_2 biosynthesis by the analyses of the expression mechanism of PGI_2 and TX synthase genes and to find new biological activities of PGI_2 and TXA_2 with the gene targeting mice of those enzymes. In this study, we have found the results described below.1. The promoter assay for PGI_2 synthase gene indicated the important promoter regions specific for the transcription in endothelial cells or neointimal vascular smooth muscle cells. 2. Cyclic strain weakly induced gene expression of PGI_2 synthase and cyclooxygenase-2 but not cyclooxygenase-l in bovine endothelial cells. 3. We produced the gene targeting mice of PGI_2 synthase. The mice was completely deficient in PGI_2 and represented their kidney abnormalities with morphological changes. The thickening of the vascular walls, atherosclerosis, and fibrosis were found in the legions. 4. The gene transfer of human PGI_2 synthase-expression vector into rat balloon-injured carotid arteries by HVJ-liposome method resulted in the increased production of PGI_2 in the vascular wall, the expression of human PGI_2 synthase in the developing neointima and significantly inhibited the neointimal formation. 5. We succeeded in the production of TX synthase gene targeting mice.