Molecular and functional identification of large neutral amino acid transporters LAT1 and LAT2 and their pharmacological relevance at the blood-brain barrier
Molecular and functional identification of large neutral amino acid transporters LAT1 and LAT2 and their pharmacological relevance at the blood-brain barrier
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DOI：
10.1211/0022357011775794
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发表时间：
2001-04-01
影响因子：
3.3
通讯作者：
Tsuji, A
中科院分区：
文献类型：
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作者：
Kido, Y;Tamai, I;Tsuji, A
我们在这里展示了 LAT1 和 LAT2（大中性氨基酸转运系统 L 的亚基）在培养的大鼠脑毛细血管内皮细胞中的分子和功能表达的证据。采用RT-PCR方法，在大鼠原代培养的脑毛细血管内皮细胞（BCEC）和永生化亚系RBEC1中检测到LAT1、LAT2和4F2抗原重链（4F2hc）的转录本。 RBEC1 的摄取特性，例如 [H-3] 亮氨酸和 L-[H-3]DOPA 摄取，与原代培养的 BCEC 相似。因此，RBEC1可能保留了大中性氨基酸摄取活性的几乎天然特性。 [H-3]RBEC1对亮氨酸的摄取显示出两个可饱和组分，并且高亲和力组分和低亲和力组分的K-m值分别为8.92+/-3.18和119+/-45μM。高亲和力组分的K-m值与LAT1非常一致，并且RBEC1的氨基酸转运选择性与LAT1相似。因此，表明LAT1对于大鼠的血脑屏障很重要。此外，低亲和力成分的 K-m 值与 LAT2 相似。这些观察结果表明，LAT1 和 LAT2 是血脑屏障中大中性氨基酸的转运蛋白。此外，我们得出结论，RBEC1 可用作体外模型，用于评估系统 L 在血脑屏障的药理学相关性。
We present here the evidence of molecular and functional expression of LAT1 and LAT2, subunits of the large neutral amino acid transporter system L, in cultured brain capillary endothelial cells of the rat. By means of the RT-PCR method, transcripts of LAT1, LAT2 and heavy chain of 4F2 antigen (4F2hc) were detected in rat primary cultured brain capillary endothelial cells (BCECs) and immortalized subline, RBEC1. The uptake properties of RBEC1, such as [H-3] leucine and L-[H-3]DOPA uptake, were similar to those of primary cultured BCECs. So, RBEC1 may retain almost native properties of the large neutral amino acid uptake activities. [H-3] Leucine uptake by RBEC1 showed two saturable components a nd the K-m va lues of the high- and low-affinity components were 8.92 +/-3.18 and 119 +/- 45 muM, respectively. The K-m value of the high-affinity component agreed well with that of LAT1 and the amino acid transport selectivity of RBEC1 was similar to that of LAT1. Therefore, it is suggested that LAT1 is important at the blood-brain barrier of rats. Additionally, the K-m value of the low-affinity component was similar to that of LAT2. These observations indicate that LAT1 and LAT2 are involved as transporters for large neutral amino acids at the blood-brain barrier. Additionally, we concluded that RBEC1 is useful as an in-vitro model for evaluation of the pharmacological relevance of system L at the blood-brain barrier.