Membrane transport mechanisms of choline in human intestinal epithelial LS180 cells
Membrane transport mechanisms of choline in human intestinal epithelial LS180 cells
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DOI：
10.1002/bdd.1917
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发表时间：
2014-12-01
影响因子：
2.1
通讯作者：
Hashimoto, Yukiya
中科院分区：
文献类型：
--
作者：
Horie, Asuka;Ishida, Kazuya;Hashimoto, Yukiya
本研究的目的是利用人肠上皮 LS180 细胞研究胆碱的膜转运机制。胆碱转运蛋白样蛋白(CTL) mRNA在LS180细胞中显着表达，表达顺序为CTL1>CTL4>CTL3>CTL2>CTL5。相比之下，其他胆碱转运蛋白、有机阳离子转运蛋白（OCT）1、OCT2和高亲和力胆碱转运蛋白1（CHT1）的mRNA表达在LS180细胞中显着降低。 5 mm 未标记的胆碱、hemicolinium-3 和胍（但不是四乙铵）抑制 LS180 细胞对 100 μm 胆碱的细胞摄取。 LS180 细胞对胆碱的摄取实际上不依赖于 Na+。细胞外 pH 值酸化会显着降低胆碱的摄取；然而，它并不会因细胞外 pH 值的碱化而增加。此外，细胞内pH值的酸化和碱化均降低了胆碱的摄取，表明LS180细胞中的胆碱摄取不受向外的H+梯度的刺激。另一方面，随着细胞外 K+ 浓度的增加，膜去极化导致胆碱的摄取减少。另外，不依赖Na+的胆碱摄取是饱和的，并且K-m值估计为108μm。这些发现表明，LS180 细胞对胆碱的摄取是膜电位依赖性的，而不是向外 H+ 梯度依赖性的。版权所有 (c) 2014 约翰·威利父子有限公司
The aim of the present study was to investigate the membrane transport mechanisms of choline using human intestinal epithelial LS180 cells. The mRNA of choline transporter-like proteins (CTLs) was expressed significantly in LS180 cells, and the rank order was CTL1>CTL4>CTL3>CTL2>CTL5. In contrast, the mRNA expression of other choline transporters, organic cation transporter (OCT) 1, OCT2 and high-affinity choline transporter 1 (CHT1), was considerably lower in LS180 cells. Five mm unlabelled choline, hemicolinium-3 and guanidine, but not tetraethylammonium, inhibited the cellular uptake of 100 mu m choline in LS180 cells. The uptake of choline into LS180 cells was virtually Na+-independent. The uptake of choline was significantly decreased by acidification of the extracellular pH; however, it was not increased by alkalization of the extracellular pH. In addition, both acidification and alkalization of intracellular pH decreased the uptake of choline, indicating that the choline uptake in LS180 cells is not stimulated by the outward H+ gradient. On the other hand, the uptake of choline was decreased by membrane depolarization along with increasing extracellular K+ concentration. In addition, the Na+-independent uptake of choline was saturable, and the K-m value was estimated to be 108 mu m. These findings suggest that the uptake of choline into LS180 cells is membrane potential-dependent, but not outward H+ gradient-dependent. Copyright (c) 2014 John Wiley & Sons, Ltd.