α- and δ-tocopherol induce expression of hepatic α-tocopherol-transfer-protein mRNA

Abstract

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.

^|^alpha;-Tocopherol Status and Expression of ^|^alpha;-Tocopherol Transfer Protein in Type 2 Diabetic Goto-Kakizaki Rats

“…In the present study, in addition to the hepatic a-TTP expression, the levels of plasma a-tocopherol were also increased in the GK rats. Several studies have explored the gene expression pattern of a-TTP under various conditions (28)(29)(30)(31)(32). a-Tocopherol administration increased hepatic a-TTP gene expression in vitamin E-depleted rats (32).…”

Trans-complementation of vector replication versus Coxsackie-adenovirus-receptor overexpression to improve transgene expression in poorly permissive cancer cells

“…Rat cytoplasmatic ␤-actin specific fragments were amplified as described previously. 52 The specificity of the amplification fragments used for labeling as hybridization probes was confirmed by direct sequencing of the amplified PCR products. Hybridization was used as recommended by the supplier (Clontech, Heidelberg, Germany).…”

Expression of Coxsackie adenovirus receptor and alphav-integrin does not correlate with adenovector targeting in vivo indicating anatomical vector barriers

“…32 P-dCTP labelling of antisense DNA probes was carried out in a PCR-like reaction as described previously 67 with one exception. For generation of the 18S-rRNA antisense probe, 6.6 m dCTP was given together with 0.26 m 32 P-dCTP in the PCR-like reaction.…”