Transport of a tripeptide, Gly-Pro-Hyp, across the porcine intestinal brush-border membrane
Transport of a tripeptide, Gly-Pro-Hyp, across the porcine intestinal brush-border membrane
复制标题
DOI：
10.1002/psc.870
复制
发表时间：
2007-07-01
影响因子：
2.1
通讯作者：
Mine, Yoshinori
中科院分区：
文献类型：
--
作者：
Aito-Inoue, Misako;Lackeyram, Dale;Mine, Yoshinori
寡肽在肠道上皮细胞的跨细胞转运在生物活性多肽如何在体内表达多种生理功能的研究中引起了极大的兴趣。据推测，在胶原序列中经常发现的三肽Gly-Pro-Hyp具有生物活性。然而，肠道上皮细胞摄取膳食二肽和三肽的机制还不是很清楚。在这项研究中，我们使用猪刷状边缘膜(BBM)囊泡来评估Gly-Pro-Hyp的摄取，因为这些囊泡在结构和功能上都可以模拟人体肠道顶膜的活体条件。本研究证实了该三肽在BBM囊泡顶端降解为自由形式的甘氨酸和二肽Pro-Hyp的过程。在BBM囊泡内环境中，在三肽的同时，还发现了二肽Pro-Hyp。我们发现Pro-Hyp的跨细胞转运被多肽转运蛋白(PEPT1)的竞争性底物(Gly-Pro)所抑制，并且是pH依赖的。这些结果表明，Gly-Pro-Hyp可以被刷状缘膜结合的氨基肽酶N部分降解以去除Gly，所产生的Pro-Hyp部分通过H+偶联的PEPT1运输到小肠上皮细胞。Gly-Pro-Hyp不能完整地穿过上皮根尖膜，并且Pro-Hyp对肠粘膜顶端蛋白水解酶具有高度的抵抗性。版权所有(C)2007欧洲肽协会和John Wiley&Sons，Ltd.
The transcellular transport of oligopeptides across intestinal epithelial cells has attracted considerable interest in investigations into how biologically active peptides express diverse physiological functions in the body. It has been postulated that the tripeptide, Gly-Pro-Hyp, which is frequently found in collagen sequences, exhibits bioactivity. However, the mechanism of uptake of dietary di- and tripeptides by intestinal epithelial cells is not well understood. In this study, we used porcine brush-border membrane (BBM) vesicles to assess Gly-Pro-Hyp uptake, because these vesicles can structurally and functionally mimic in vivo conditions of human intestinal apical membranes. The present study demonstrated the time-dependent degradation of this tripeptide into the free-form Gly and a dipeptide, Pro-Hyp, on the apical side of the BBM vesicles. In parallel with the hydrolysis of the tripeptide, the dipeptide Pro-Hyp was identified in the BBM intravesicular space environment. We found that the transcellular transport of Pro-Hyp across the BBM was inhibited by the addition of a competitive substrate (Gly-Pro) for peptide transporter (PEPT1) and was pH-dependent. These results indicate that Gly-Pro-Hyp can be partially hydrolyzed by the brush-border membrane-bound aminopeptidase N to remove Gly, and that the resulting Pro-Hyp is, in part, transported into the small intestinal epithelial cells via the H+-coupled PEPT1. Gly-Pro-Hyp cannot cross the epithelial apical membrane in an intact form, and Pro-Hyp is highly resistant to hydrolysis by intestinal mucosal apical proteases. Copyright (C) 2007 European Peptide Society and John Wiley & Sons, Ltd.