Transport of amino acid-based prodrugs by the Na+- and Cl- -coupled amino acid transporter ATB0,+ and expression of the transporter in tissues amenable for drug delivery
Transport of amino acid-based prodrugs by the Na+- and Cl- -coupled amino acid transporter ATB0,+ and expression of the transporter in tissues amenable for drug delivery
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DOI：
10.1124/jpet.103.057109
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发表时间：
2004-03-01
影响因子：
3.5
通讯作者：
Ganapathy, ME
中科院分区：
文献类型：
--
作者：
Hatanaka, T;Haramura, M;Ganapathy, ME
我们评估了Na+和Cl-偶联氨基酸转运蛋白ATB（0，+）作为氨基酸前药递送系统的潜力。免疫荧光分析表明，ATB（0，+）在大肠腔和肺气道内衬细胞的腔表面以及各种眼组织（包括结膜上皮，这些组织易于进行药物递送）中大量表达。我们筛选了各种β-羧基衍生物的天冬氨酸和γ-羧基衍生物的谷氨酸作为潜在的基板，这种转运使用异源表达系统。在表达克隆ATB（0，+）的哺乳动物细胞中，几种天冬氨酸和谷氨酸衍生物抑制甘氨酸通过ATB（0，+）转运。ATB（0，+）介导的运输这些衍生物的直接证据，获得非洲爪蟾卵母细胞使用电生理方法。将异源表达ATB（0，+）的卵母细胞暴露于作为模型衍生物的天冬氨酸β-苄酯，以Na+-和Cl-依赖性方式诱导内向电流，Na+/Cl-/天冬氨酸β-苄酯化学计量比为2：1：1。ATB（0，+）不仅转运天冬氨酸的β-羧基衍生物和谷氨酸的β-羧基衍生物，而且转运伐昔洛韦，伐昔洛韦是阿昔洛韦与缬氨酸的α-羧基酯。在两种异源表达系统中均证实伐昔洛韦通过ATB（0，+）转运。这一过程依赖于Na+和Cl-。ATB（0，+）转运伐昔洛韦的能力与肽转运蛋白PEPT 1相当。这些发现表明ATB（0，+）作为基于氨基酸的药物和前药的递送系统具有显著的潜力。
We evaluated the potential of the Na+- and Cl--coupled amino acid transporter ATB(0,+) as a delivery system for amino acid-based prodrugs. Immunofluorescence analysis indicated that ATB(0,+) is expressed abundantly on the luminal surface of cells lining the lumen of the large intestine and the airways of the lung and in various ocular tissues, including the conjunctival epithelium, the tissues easily amenable for drug delivery. We screened a variety of beta-carboxyl derivatives of aspartate and gamma-carboxyl derivatives of glutamate as potential substrates for this transporter using heterologous expression systems. In mammalian cells expressing the cloned ATB(0,+), several of the aspartate and glutamate derivatives inhibited glycine transport via ATB(0,+). Direct evidence for ATB(0,+)-mediated transport of these derivatives was obtained in Xenopus laevis oocytes using electrophysiological methods. Exposure of oocytes, which express ATB(0,+) heterologously, to aspartate beta-benzyl ester as a model derivative induced inward currents in a Na+- and Cl--dependent manner with a Na+/Cl-/ aspartate beta-benzyl ester stoichiometry of 2: 1: 1. ATB(0,+) transported not only the beta-carboxyl derivatives of aspartate and the beta-carboxyl derivatives of glutamate but also valacyclovir, which is an alpha-carboxyl ester of acyclovir with valine. The transport of valacyclovir via ATB(0,+) was demonstrable in both heterologous expression systems. This process was dependent on Na+ and Cl-. The ability of ATB(0,+) to transport valacyclovir was comparable with that of the peptide transporter PEPT1. These findings suggest that ATB(0,+) has significant potential as a delivery system for amino acid-based drugs and prodrugs.