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Morphological studies on the transfer machinery molecules in the blood-tissue barriers.

血液组织屏障中转移机械分子的形态学研究。

基本信息

批准号：
07457002
负责人：
TAKATA Kuniaki
金额：
$ 4.8万
依托单位：
GUNMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

项目摘要

Transfer machimery in the blood-tissue barriers were studied using isoform-specific antibodies. In barrieres made of a single epithelial or endothelial cell layrs, GLUT1 sugar transporter was localized at plasma membranes of both apical and basolateral domains of them. In barriers composed of double-epithelial cell layrs such as the epithelium of the ciliary body (blood-aqueous barriers) and the rat trophoblasts (placental barrier), GLUT1 was abundant at plasma membranes located at each side of the barrier layr. Two adjacent cell layrs were connected by numerous gap junctions of connexin 43 or connexin 26. Considering the location and abundance of transporters and connexin isoforms, I proposed the glucose transfer machinery in these double-cell barriers as follows : entry of glucose into the first barrier cell layr via GLUT1 ; transfer to the second barrier layr via connexin 43 (or 26) ; exit from the second barrier cell layr via GLUT1. These results suggest that transfer of substances with low-molecular weight is mediated with the combination of specific transporters (or channels) connexin isoforms and specific transporters (or channels) aligned in series. Molecular mechanism for specific localization of sugar transporter molecules was assessed by expressing GLUT1 and GLUT5 sugar transporter genes and their chimeras in cultured epithelial cells. Immunocytochemical analysis revealed that cytoplasmic loop domain plays an important role in determining their localization on the plasma membrane in polarized epithelial cells.

使用同种型特异性抗体研究了血液组织屏障中的转移机制。在单层上皮或内皮细胞构成的屏障中，GLUT 1糖转运蛋白定位于其顶侧和底侧区域的质膜上。在由双上皮细胞层组成的屏障中，如睫状体上皮（血-水屏障）和大鼠滋养层（胎盘屏障），GLUT 1在位于屏障层两侧的质膜上丰富。相邻两层细胞间由大量连接蛋白43或连接蛋白26的缝隙连接。考虑到转运蛋白和连接蛋白异构体的位置和丰度，我提出了这些双细胞屏障中的葡萄糖转运机制如下：葡萄糖通过GLUT 1进入第一屏障细胞层;通过连接蛋白43（或26）转移到第二屏障细胞层;通过GLUT 1从第二屏障细胞层离开。这些结果表明，低分子量物质的转移是由特定的转运蛋白（或通道）连接蛋白亚型和特定的转运蛋白（或通道）串联排列的组合介导的。通过在培养的上皮细胞中表达GLUT 1和GLUT 5糖转运蛋白基因及其嵌合体来评估糖转运蛋白分子特异性定位的分子机制。免疫细胞化学分析表明，胞浆环结构域起着重要的作用，在决定他们的定位在质膜极化上皮细胞。