Shaw H M, Huang C j
Laboratory of Nutritional Biochemistry, Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan 10716.
J Nutr. 1998 Dec;128(12):2348-54. doi: 10.1093/jn/128.12.2348.
To study how the expression of alpha-tocopherol transfer protein (alpha-TTP) and its mRNA are affected by protein and vitamin E status, Long-Evans male weanling rats were fed a vitamin E-deficient (DE), high vitamin E (HE, 5 g/kg diet of all-rac-alpha-tocopheryl acetate) or control (C) diet for 12 wk in Experiment 1; and fed a low-protein (LP) or control (C) diet for 6 wk in Experiment 2. The high and deficient vitamin E status of HE and DE groups in Experiment 1 were confirmed by changes in plasma pyruvate kinase activity as well as the concentrations of alpha-tocopherol in plasma and liver. As shown by the Northern and Western Blot Analysis, the expression of alpha-TTP in the liver of the DE group was significantly lower than, while that of the HE group was not different from, that of the controls. In contrast, the alpha-TTP mRNA levels did not differ among the C, DE and HE groups. alpha-Tocopherol in most peripheral tissues of rats fed the LP diet in Experiment 2 was significantly lower than that of the C. Both the alpha-TTP and its mRNA were significantly lower in the LP group than in the C. The results suggested that dietary vitamin E does not affect alpha-TTP gene expression except that the protein levels in the liver were lowered by vitamin E deficiency. On the other hand, protein inadequacy appeared to down-regulate the expression of the alpha-TTP gene.
为研究α-生育酚转运蛋白（α-TTP）及其mRNA的表达如何受蛋白质和维生素E状态的影响，在实验1中，给Long-Evans雄性断乳大鼠喂食维生素E缺乏（DE）、高维生素E（HE，5 g/kg饮食的消旋-α-生育酚醋酸酯）或对照（C）饮食12周；在实验2中，给大鼠喂食低蛋白（LP）或对照（C）饮食6周。通过血浆丙酮酸激酶活性以及血浆和肝脏中α-生育酚浓度的变化，证实了实验1中HE和DE组维生素E状态的高低情况。如Northern和Western印迹分析所示，DE组肝脏中α-TTP的表达显著低于对照组，而HE组与对照组无差异。相比之下，C、DE和HE组之间的α-TTP mRNA水平无差异。在实验2中，喂食LP饮食的大鼠大多数外周组织中的α-生育酚显著低于C组。LP组中的α-TTP及其mRNA均显著低于C组。结果表明除维生素E缺乏会降低肝脏中的蛋白质水平外，饮食中的维生素E不影响α-TTP基因表达。另一方面，蛋白质不足似乎会下调α-TTP基因的表达。
