Coxsackievirus and adenovirus receptor, a tight junction membrane protein, is expressed in glomerular podocytes in the kidney
Coxsackievirus and adenovirus receptor, a tight junction membrane protein, is expressed in glomerular podocytes in the kidney
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DOI：
10.1097/01.lab.0000073307.82991.cc
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发表时间：
2003-06-01
影响因子：
5
通讯作者：
Yamamoto, T
中科院分区：
文献类型：
--
作者：
Nagai, M;Yaoita, E;Yamamoto, T
在肾病中，足细胞的过滤狭缝大大变窄，并且狭缝隔膜被紧密接触的连接部移位。冷冻断裂研究表明，新形成的连接由紧密连接和间隙连接组成。几种紧密连接蛋白被认为是膜的组成部分，包括闭合蛋白和封闭蛋白，但它们都没有在足细胞中发现。柯萨奇病毒和腺病毒受体（CAR）最近被鉴定为病毒受体，其是在细胞外区域具有两个Ig样结构域的46-kDa整合膜蛋白。在极化的上皮细胞中，CAR在紧密连接处表达，在那里它与ZO-1结合，并在大分子和离子运动的屏障中发挥作用。在本研究中，我们研究了CAR在嘌呤霉素氨基糖苷（PAN）处理的大鼠肾脏和用硫酸鱼精蛋白（PS）灌注15分钟的大鼠肾脏中的表达和定位。这两种实验模型都已用于诱导足细胞中的紧密连接。核糖核酸酶保护试验和蛋白质印迹分析显示PAN肾病期间肾小球中CAR转录物和蛋白质明显增加，但PS灌注肾小球中没有增加。免疫组化显示PAN肾病和PS灌注后肾小球毛细血管壁的CAR染色强度沿着显著增加。免疫电子显微镜检查表明，在这两个模型中，免疫金颗粒的CAR沿着毛细血管壁主要发现在密切的细胞接触部位的足细胞，但很少发现在狭缝隔膜。在培养的足细胞中，CAR定位于细胞-细胞接触部位。CAR分布与ZO-1相同，与间隙连接蛋白connexin 43不同。这些发现表明，CAR是足细胞紧密连接的一个不可或缺的膜组件，并且CAR在足细胞中的表达在转录水平和蛋白质的再分布中受到调节。
In nephrosis, filtration slits of podocytes are greatly narrowed, and slit diaphragms are displaced by junctions with close contact. Freeze-fracture studies have shown that the newly formed junctions consist of tight junctions and gap junctions. Several tight-junction proteins are known as integral membrane components, including occludin and claudins; but none of them have been found in podocytes. Coxsackievirus and adenovirus receptor (CAR) has recently been identified as a virus receptor that is a 46-kDa integral membrane protein with two Ig-like domains in the extracellular region. In polarized epithelial cells, CAR is expressed at the tight junction, where it associates with ZO-1 and plays a role in the barrier to the movement of macromolecules and ions. In the present study, we investigated the expression and localization of CAR in rat kidneys treated with puromycin aminonucleoside (PAN) and in rat kidneys perfused for 15 minutes with protamine sulfate (PS). Both the experimental models have been used to induce tight junctions in podocytes. Ribonuclease protection assay and Western blot analysis revealed a distinct increase of CAR transcript and protein in glomeruli during PAN nephrosis but no increase in glomeruli by PS perfusion. Immunohistochemistry revealed a significant increase in CAR staining intensity along the glomerular capillary wall in PAN nephrosis and after PS perfusion. Immunoelectron microscopy demonstrated in both the models that the immunogold particles for CAR along the capillary wall were found predominantly at close cell-cell contact sites of podocytes but were rarely found at slit diaphragms. In cultured podocytes, CAR was localized at cell-cell contact sites. CAR distribution was identical to that of ZO-1 and different from that of a gap junction protein, connexin43. These findings indicate that CAR is an integral membrane component of tight junction in podocytes and that CAR expression in podocytes is regulated at the transcriptional level and in the redistribution of protein.