Slit Diaphragms Contain Tight Junction Proteins
Slit Diaphragms Contain Tight Junction Proteins
复制标题
DOI：
10.1681/asn.2008101117
复制
发表时间：
2009-07-01
影响因子：
13.6
通讯作者：
Farquhar, Marilyn G.
中科院分区：
文献类型：
--
作者：
Fukasawa, Hirotaka;Bornheimer, Scott;Farquhar, Marilyn G.
缝隙膜片是肾小球过滤设备的必不可少的组成部分，因为这些连接的变化是蛋白尿疾病的标志。被认为是专门的粘附连接的缝隙膜片既包含独特的膜蛋白（例如肾蛋白，Podocin和Neph1），又包含典型的粘附蛋白（例如P-钙粘蛋白，脂肪，脂肪和Catenins）。缝隙隔膜是否也含有紧密的连接蛋白是未知的。在这里，免疫荧光，免疫金标记和细胞分馏表明，大鼠缝隙隔膜包含紧密的连接蛋白JAM-A（连接粘附分子A），occludin和cing蛋白。我们通过辅助，共免疫沉淀和下拉测定法发现了与肾蛋白，Podocin，CD2AP，ZO-1和NEPH1相同的蛋白质复合物中的这些蛋白质。泛肾脏增加了肾小球的JAM-A，occludin，Cingulin和ZO-1的蛋白质水平，并松开了它们与肌动蛋白细胞骨架上的附着。这些数据通过证明存在紧密的连接蛋白的存在来扩展有关缝隙隔膜分子组成的电流信息，尽管裂缝隔膜缺乏紧密连接的特征形态特征。这些蛋白质对缝隙隔膜组装和潜在信号级联反应的贡献需要进一步研究。
Slit diaphragms are essential components of the glomerular filtration apparatus, as changes in these junctions are the hallmark of proteinuric diseases. Slit diaphragms, considered specialized adherens junctions, contain both unique membrane proteins (e.g., nephrin, podocin, and Neph1) and typical adherens junction proteins (e.g., P-cadherin, FAT, and catenins). Whether slit diaphragms also contain tight junction proteins is unknown. Here, immunofluorescence, immunogold labeling, and cell fractionation demonstrated that rat slit diaphragms contain the tight junction proteins JAM-A (junctional adhesion molecule A), occludin, and cingulin. We found these proteins in the same protein complexes as nephrin, podocin, CD2AP, ZO-1, and Neph1 by cosedimentation, coimmunoprecipitation, and pull-down assays. PAN nephrosis increased the protein levels of JAM-A, occludin, cingulin, and ZO-1 several-fold in glomeruli and loosened their attachment to the actin cytoskeleton. These data extend current information about the molecular composition of slit diaphragms by demonstrating the presence of tight junction proteins, although slit diaphragms lack the characteristic morphologic features of tight junctions. The contribution of these proteins to the assembly of slit diaphragms and potential signaling cascades requires further investigation.