Production and application of novel model animals with an oxidative stress

维生素E （a-生育酚）是一种脂溶性抗氧化剂，通过血浆脂蛋白在体内运输。a-生育酚通过脂蛋白被肝脏吸收，被认为以极低密度脂蛋白（VLDL）的形式重新分泌到血浆中，α -生育酚转移蛋白（alpha-tocopherol transfer protein, alpha-tocopherol transfer protein, alpha-tocopherol transfer protein, alpha-tocopherol transfer protein, alpha-tocopherol transfer protein, alphaTTP）是一种胞质肝蛋白，在血浆维生素E的有效循环中起重要作用。我们发现α -生育酚的分泌在表达α -生育酚的细胞中比在缺乏α -生育酚的匹配细胞中更有效。Brefeldin A通过破坏高尔基体抑制VLDL分泌，但对α -生育酚分泌无影响，说明α -生育酚分泌与VLDL分泌不偶联。在测试的其他药物中，只有25-羟基胆固醇（一种胆固醇代谢调节剂）能抑制α -孕酚的分泌。这些结果表明，α -生育酚具有刺激细胞α -生育酚分泌到细胞外介质的功能，并且该反应利用一种新的非高尔基体介导的途径，可能与细胞胆固醇代谢或运输有关。我们研究了α attp识别所需的维生素E类似物的结构特征。有趣的是，从大鼠吸收-妊娠试验中获得的相对亲和力和已知的生物活性之间存在线性关系。因此，维生素E类似物对α - attp的亲和力是其生物活性的关键决定因素之一。alphaTTP仅在肝脏中表达，但在一些大鼠组织（包括脑、脾、肺和肾）中可以检测到低水平的alphaTTP信息。原位杂交组织化学显示，在大脑中，主要在小脑皮层检测到α - attp转录物。在小脑皮层，杂交信号主要在伯格曼胶质细胞中检测到。我们最近成功地建立了α - attp基因敲除小鼠。小鼠血浆维生素E水平几乎检测不到，杂合子约为野生型小鼠的一半。这些数据清楚地表明，α - attp是血浆维生素E水平的主要决定因素。少

Vitamin E (a-tocopherol) is a fat-soluble antioxidant that is transported by plasma lipoproteins in the body. a-tocopherol taken up by the liver with lipoprotein is thought to be re-secreted into the plasma in very low density lipoprotein (VLDL), alpha-tocopherol transfer protein (alphaTTP), which was recently identified as a product of the causative gene for familial isolated vitamin E deficiency, is a cytosolic liver protein and plays an important role in the efficient recycling of plasma vitamin E.Using cell culture system, we found that the secretion of alpha-tocopherol is more efficient in cells expressing alphaTTP than in matched cells lacking alphaTTP.Brefeldin A, which inhibits VLDL secretion by disrupting the Golgi apparatus, has no effect on alpha-tocopherol secretion, indicating that alphaTTP-mediated alpha-tocopherol secretion is not coupled to VLDL secretion. Among other agents tested, only 25-hydroxycholesterol, a modulator of cholesterol metabolism, inhibits alpha-tocoph … More erol secretion. These results suggest that alphaTTP functions to stimulate secretion of cellular alpha-tocopherol into the extracellular medium and that the reaction utilizes a novel non-Golgi mediated pathway which may be linked to cellular cholesterol metabolism or transport. We examined the structural characteristics of vitamin E analogs required for recognition by alphaTTP.Interestingly, there is a linear relationship between the relative affinity and the known biological activity obtained from the rat resorption-gestation assay. Thus the affinity of vitamin E analogs for alphaTTP is one of the critical determinants of their biological activity. alphaTTP is exclusively expressed in the liver, but the message for alphaTTP was detectable at low levels in some rat tissues including brain, spleen, lung and kidney. In the brain, the alphaTTP transcript is detected predominantly in the cerebellar cortex, as revealed by in situ hybridization histochemistry. In the celebellar cortex, the hybridization signals are detected mostly in the Bergmann glial cells. We have recently succeeded in establishing the knock out mice for alphaTTP.The plasma vitamin E level of the mice is almost undetectable and that of heterozygote is about half that of wild type mice. These data clearly demonstrate that alphaTTP is a major determinant of plasma vitamin E level. Less