Fechner H, Schlame M, Guthmann F, Stevens P A, Rüstow B
Department of Neonatology, University Hospital Charité, Humboldt University, D-10098 Berlin, Federal Republic of Germany.
Biochem J. 1998 Apr 15;331 ( Pt 2)(Pt 2):577-81. doi: 10.1042/bj3310577.
alpha-Tocopherol transfer protein (alpha-TTP) supplements nascent very-low-density lipoprotein (VLDL) preferentially with alpha-tocopherol by selecting the alpha-isomers against other stereoisomers of tocopherol. It is exclusively expressed in liver. We investigated whether the expression of the hepatic alpha-TTP can be induced by dietary tocopherols. Vitamin E-depleted rats were fed with a diet containing alpha- and delta-tocopherol (ratio 1:3). The expression of alpha-TTP mRNA was measured in liver tissue. The ratio of tocopherol stereoisomers was determined in plasma, plasma lipoproteins and tissues to measure the metabolic action of alpha-TTP. Refeeding a diet containing either alpha- or delta-tocopherol, or both, caused a steady increase of the expression of alpha-TTP mRNA. In parallel the alpha/delta-tocopherol ratio increased in plasma, VLDL, high-density lipoprotein and low-density lipoprotein as well as in liver tissue, when the diet was fed containing both isomers. The alpha-tocopherol/delta-tocopherol ratio of heart, kidney, lung, lamellar bodies of lung and in lung lavage showed no or a comparatively low increase. The data show that both tocopherol isomers were able to induce alpha-TTP mRNA in rat liver and, thus, the ability of liver to select for the alpha-isomer. On the other hand, tocopherol depletion did not change the expression of hepatic alpha-TTP mRNA in the rat.
α-生育酚转运蛋白（α-TTP）通过选择生育酚的α-异构体而非其他立体异构体，优先用α-生育酚补充新生的极低密度脂蛋白（VLDL）。它仅在肝脏中表达。我们研究了膳食生育酚是否能诱导肝脏α-TTP的表达。将维生素E缺乏的大鼠喂食含有α-生育酚和δ-生育酚（比例为1:3）的饮食。测量肝脏组织中α-TTP mRNA的表达。测定血浆、血浆脂蛋白和组织中生育酚立体异构体的比例，以衡量α-TTP的代谢作用。重新喂食含有α-生育酚或δ-生育酚或两者的饮食会导致α-TTP mRNA的表达稳步增加。同时，当喂食含有两种异构体的饮食时，血浆、VLDL、高密度脂蛋白和低密度脂蛋白以及肝脏组织中的α/δ-生育酚比例增加。心脏、肾脏、肺、肺板层小体和肺灌洗中的α-生育酚/δ-生育酚比例没有增加或增加相对较低。数据表明，两种生育酚异构体都能够诱导大鼠肝脏中的α-TTP mRNA，从而诱导肝脏选择α-异构体的能力。另一方面，生育酚缺乏并没有改变大鼠肝脏中α-TTP mRNA的表达。
