Uchida Yasuo, Zhang Zhengyu, Tachikawa Masanori, Terasaki Tetsuya
Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan.
J Neurochem. 2015 Sep;134(6):1104-15. doi: 10.1111/jnc.13147. Epub 2015 Jun 8.
The purpose of this study was to determine absolute protein expression levels of transporters in rat choroid plexus, that is, the blood-cerebrospinal fluid barrier, and to compare them with the levels in the human choroid plexus. Plasma membrane fractions were prepared from pooled, freshly isolated choroid plexuses of 30 male Wistar rats and from frozen choroid plexus of one male human donor. Protein expression levels of 54 rat and 121 human molecules were measured, using a quantitative targeted absolute proteomics technique. In rat, oatp1a5 showed the most abundant protein expression (30.3 fmol/μg protein), and its expression level was 3.1-, 4.5-, 5.5-, 8.4-, 9.0-, 9.9-, 22-, 91-, and 95-fold greater than those of glut1, oatp1c1, mrp1, mct1, oat3, pept2, mrp4, bcrp, and mdr1a, respectively. OATP1A2 (a possible homolog of rat oatp1a5), OATP1C1 and PEPT2 were not detected in human choroid plexus. MRP1, OAT3, and MRP4 showed 4.0-, 1.8-, and 1.7-fold smaller expression levels in human than rat, respectively. MATE1 was detected in human, but not rat, and its expression level (8.61 fmol/μg protein) was the highest among the xenobiotic transporters examined in human choroid plexus. These findings should be useful for understanding rat blood-cerebrospinal fluid barrier function and its differences from that in human. This is the first study clarifying the absolute protein expression levels of many transporters in the plasma membrane fractions of rat and human choroid plexuses, that is, blood cerebrospinal fluid barrier, by means of quantitative targeted absolute proteomics (QTAP) technique. This study also identified the protein expressions of some transporters including MATE1 and ABCA8 in the choroid plexus for the first time.
本研究的目的是确定大鼠脉络丛（即血脑脊髓液屏障）中转运蛋白的绝对蛋白表达水平，并将其与人类脉络丛中的水平进行比较。从30只雄性Wistar大鼠新鲜分离的合并脉络丛以及一名男性人类供体的冷冻脉络丛中制备质膜组分。使用定量靶向绝对蛋白质组学技术测量了54种大鼠和121种人类分子的蛋白质表达水平。在大鼠中，oatp1a5显示出最丰富的蛋白质表达（30.3 fmol/μg蛋白质），其表达水平分别比glut1、oatp1c1、mrp1、mct1、oat3、pept2、mrp4、bcrp和mdr1a高3.1倍、4.5倍、5.5倍、8.4倍、9.0倍、9.9倍、22倍、91倍和95倍。在人类脉络丛中未检测到OATP1A2（大鼠oatp1a5的可能同源物）、OATP1C1和PEPT2。MRP1、OAT3和MRP4在人类中的表达水平分别比大鼠低4.0倍、1.8倍和1.7倍。在人类中检测到了MATE1，但在大鼠中未检测到，其表达水平（8.61 fmol/μg蛋白质）在人类脉络丛中检测的外源性转运蛋白中最高。这些发现对于理解大鼠血脑脊髓液屏障功能及其与人类的差异应该是有用的。这是第一项通过定量靶向绝对蛋白质组学（QTAP）技术阐明大鼠和人类脉络丛（即血脑脊髓液屏障）质膜组分中许多转运蛋白绝对蛋白表达水平的研究。本研究还首次鉴定了脉络丛中包括MATE1和ABCA8在内的一些转运蛋白的蛋白质表达。
