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A_2(TXA_2)是心血管系统中具有很强生物活性的脂质生物因子，参与血栓形成和动脉粥样硬化等疾病。最近，我们发现PGI_2和TX合成酶不仅在心血管组织中表达，而且在免疫系统和生殖组织中也有表达。本课题的目的是通过对PGI2和TXA2合成酶基因表达机制的分析，明确PGI2和TXA2生物合成的调控机制，并利用这些酶的基因靶向寻找PGI2和TXA2的新生物活性。在本研究中，我们发现了如下所述的结果。对PGI2合成酶基因的启动子分析表明，该基因在血管内皮细胞或新生血管平滑肌细胞中具有转录特异性的重要启动子区域。2.循环应变弱诱导牛内皮细胞PGI_2合成酶和环氧合酶-2基因表达，但不诱导环氧合酶-L基因表达。3.建立了PGI_2合成酶基因打靶小鼠。小鼠体内PGI_2完全缺乏，表现为肾脏异常和形态改变。在军团中发现血管壁增厚、动脉粥样硬化和纤维化。4.HVJ-脂质体法将人PGI_2合成酶表达载体导入大鼠颈动脉球囊损伤后，可增加血管壁中PGI_2的生成，增加新生内膜中人PGI_2合成酶的表达，并显著抑制新生内膜的形成。5.成功地制备了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.