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，由体内的血浆脂蛋白转运。被肝脏与脂蛋白一起摄取的α-生育酚被认为以极低密度脂蛋白（VLDL）、α-生育酚转移蛋白最近被鉴定为家族性孤立性维生素E缺乏症的致病基因的产物的α TTP（alphaTTP）是胞质肝蛋白，并且在血浆维生素E的有效再循环中起重要作用。我们发现α-生育酚的分泌在表达α-TTP的细胞中比在缺乏α-TTP的匹配细胞中更有效。通过破坏高尔基体来抑制VLDL分泌的布雷菲德菌素A对α-生育酚分泌没有影响，表明α-TTP介导的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，一种胆固醇代谢的调节剂， ...更多信息 雌激素分泌这些结果表明，alphaTTP的功能，以刺激分泌细胞α-生育酚到细胞外介质，该反应利用一种新的非高尔基介导的途径，这可能是连接到细胞胆固醇代谢或运输。我们研究了维生素E类似物识别所需的alphaTTP的结构特征。有趣的是，有一个相对亲和力和已知的生物活性之间的线性关系，从大鼠吸收妊娠试验。因此，维生素E类似物对alphaTTP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，但在包括脑、脾、肺和肾在内的一些大鼠组织中可检测到低水平的alphaTTP信息。在大脑中，α TTP转录主要在小脑皮质中检测到，如原位杂交组织化学所示。在小脑皮质中，杂交信号主要在Bergmann胶质细胞中检测到。我们最近成功地建立了α TTP基因敲除小鼠，其血浆维生素E水平几乎检测不到，杂合子小鼠的血浆维生素E水平约为野生型小鼠的一半。这些数据清楚地表明，α TTP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