Transport of vitamin E by differentiated Caco-2 cells
Transport of vitamin E by differentiated Caco-2 cells
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DOI：
10.1194/jlr.m500523-jlr200
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发表时间：
2006-06-01
影响因子：
6.5
通讯作者：
Hussain, M. Mahmood
中科院分区：
文献类型：
--
作者：
Anwar, Kamran;Kayden, Herbert J.;Hussain, M. Mahmood
在肝细胞中，维生素 E 通过外排途径分泌，并被认为与胞外载脂蛋白 B (apoB) 脂蛋白相关。肠道细胞摄取、细胞内运输和分泌膳食维生素 E 的分子机制尚不清楚。我们观察到，低浓度的 Tween-40 更有利于维生素 E 的溶解和递送至分化的 Caco-2 细胞，而高浓度的 Tween-40 和血清则抑制这种吸收。维生素E的吸收最初很快，然后达到饱和。亚细胞定位表明维生素 E 主要积累在微粒体膜中。油酸 (OA) 处理可诱导乳糜微粒组装和分泌，并以时间依赖性方式减少微粒体膜结合的维生素 E。为了研究分泌，用维生素 E 对分化的 Caco-2 细胞进行脉冲标记，并在存在和不存在 OA 的情况下进行追踪。在没有 OA 的情况下，维生素 E 与肠道高密度脂蛋白 (I-HDL) 相关，而 OA 处理的细胞则分泌维生素 E、I-HDL 和乳糜微粒。没有观察到维生素 E 在这些脂蛋白之间的细胞外转移。格列本脲是 ABCA1 的拮抗剂，部分抑制 I-HDL 的分泌，而血浆 HDL 则增加维生素 E 的流出。微粒体甘油三酯转移蛋白的拮抗剂布雷菲德菌素 A 和莫能菌素特异性抑制乳糜微粒的维生素 E 分泌。这些研究表明，Caco-2 细胞吸收的维生素 E 储存在微粒体膜中，并与乳糜微粒和 I-HDL 一起分泌。通过 I-HDL 转运可能有助于接受大剂量口服维生素的无β脂蛋白血症患者的维生素 E 吸收。
In hepatocytes, vitamin E is secreted via the efflux pathway and is believed to associate with apolipoprotein B (apoB)-lipoproteins extracellularly. The molecular mechanisms involved in the uptake, intracellular trafficking, and secretion of dietary vitamin E by the intestinal cells are unknown. We observed that low concentrations of Tween-40 were better for the solubilization and delivery of vitamin E to differentiated Caco-2 cells, whereas high concentrations of Tween-40 and sera inhibited this uptake. Vitamin E uptake was initially rapid and then reached saturation. Subcellular localization revealed that vitamin E primarily accumulated in microsomal membranes. Oleic acid (OA) treatment, which induces chylomicron assembly and secretion, decreased microsomal membrane-bound vitamin E in a time-dependent manner. To study secretion, differentiated Caco-2 cells were pulse-labeled with vitamin E and chased in the presence and absence of OA. In the absence of OA, vitamin E was associated with intestinal high density lipoprotein (I-HDL), whereas OA-treated cells secreted vitamin E with I-HDL and chylomicrons. No extracellular transfer of vitamin E between these lipoproteins was observed. Glyburide, an antagonist of ABCA1, partially inhibited its secretion with I-HDL, whereas plasma HDL increased vitamin E efflux. An antagonist of microsomal triglyceride transfer protein, brefeldin A, and monensin specifically inhibited vitamin E secretion with chylomicrons. These studies indicate that vitamin E taken up by Caco-2 cells is stored in the microsomal membranes and secreted with chylomicrons and I-HDL. Transport via I-HDL might contribute to vitamin E absorption in patients with abetalipoprotein-emia receiving large oral doses of the vitamin.