Functional and molecular characterization of adenosine transport at the rat inner blood-retinal barrier
Functional and molecular characterization of adenosine transport at the rat inner blood-retinal barrier
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DOI：
10.1016/j.bbamem.2006.01.011
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发表时间：
2006-01-01
影响因子：
3.4
通讯作者：
Hosoya, K
中科院分区：
文献类型：
--
作者：
Nagase, K;Tomi, M;Hosoya, K
本研究的目的是表征内血视网膜屏障（内BRB）的腺苷转运系统。条件永生化的大鼠视网膜毛细血管内皮细胞系（TR-iBRB 2），用作内BRB的体外模型，表达平衡型核苷转运蛋白1（ENT 1）、ENT 2、浓缩型核苷转运蛋白2（CNT 2）和CNT 3 mRNA。TR-iBRB 2细胞表现出Na+非依赖性和浓度依赖性的[H-3]腺苷摄取，Michaelis-Menten常数为28.5 μ M，最大摄取速率为814 pmol/（min mg蛋白）。[H-3] TR-iBRB 2细胞的腺苷摄取被2 mM腺苷、mosine、尿苷和胸苷强烈抑制。另一方面，这一过程不受100 nM硝基苄基巯基嘌呤核苷和双嘧达莫抑制。这些摄取研究表明ENT 2参与TR-iBRB 2细胞的[H-3]腺苷摄取。实时荧光定量PCR显示ENT 2 mRNA的表达是ENT 1 mRNA的5.5倍。一项体内研究表明，[H-3]腺苷从血液转运到视网膜，并受到腺苷和胸苷的显著抑制。这项研究的结果表明，ENT 2最有可能介导腺苷转运在内部BRB，并预计将发挥重要作用，在调节腺苷浓度的视网膜。(c)2006 Elsevier B. V.保留所有权利。
The purpose of the present study was to characterize the adenosine transport system(s) at the inner blood-retinal barrier (inner BRB). A conditionally immortalized rat retinal capillary endothelial cell line (TR-iBRB2), used as an in vitro model of the inner BRB, expresses equilibrative nucleoside transporter 1 (ENT1), ENT2, concentrative nucleoside transporter 2 (CNT2), and CNT3 mRNAs. TR-iBRB2 cells exhibited an Na+-independent and concentration-dependent [H-3]adenosine uptake with a Michaelis-Menten constant of 28.5 mu M and a maximum uptake rate of 814 pmol/(min mg protein). [H-3]Adenosine uptake by TR-iBRB2 cells was strongly inhibited by 2 mM adenosine, mosine, uridine, and thymidine. On the other hand, this process was not inhibited by 100 nM nitrobenzylmercaptopurine riboside and dipyridamole. These uptake studies suggest that ENT2 is involved in [H-3]adenosine uptake by TR-iBRB2 cells. Quantitative real-time PCR revealed that the expression of ENT2 mRNA is 5.5-fold greater than that of ENT1 mRNA. An in vivo study suggested that [H-3]adenosine is transported from the blood to the retina and significantly inhibited by adenosine and thymidine. The results of this study show that ENT2 most likely mediates adenosine transport at the inner BRB and is expected to play an important role in regulating the adenosine concentration in the retina. (c) 2006 Elsevier B.V. All rights reserved.