Defense mechanism of glomerular visceral epithelial cells against stress

与肾小管上皮细胞相比，哺乳动物的肾小球内脏上皮细胞（VEC）含有丰富的中间纤维（IF）。对从两栖动物到哺乳动物的广泛研究表明，这种特性在低等脊椎动物中很常见，表明IF在VEC中起着重要作用。大鼠血管内皮细胞表达结蛋白。在Masugi肾炎中，结蛋白的染色强度与抗GBM抗血清的注射剂量和蛋白尿的量平行。在嘌呤霉素肾病中，通过Western印迹和免疫染色显示VEC中结蛋白的增加和减少与蛋白尿平行。这些结果表明，结蛋白在血管内皮细胞表达的影响，在应激条件下，如肾病。Plectin是一种IF相关蛋白，被认为是IF的一般细胞质交联元件。取决于细胞类型，主要通过细胞质、在细胞周边或在这两个位置中发现网蛋白。VEC独特地显示主要附着在核周区域的网蛋白。嘌呤霉素肾病细胞质染色增强。我们推测，丰富的IF和独特的分布在血管内皮细胞的功能，以抵抗机械应力产生的超滤液从狭缝隔膜和脉冲毛细血管壁。

Glomerular visceral epithelial cells (VECs) in mammals contain abundant intermediate filaments (IFs) in comparison with tubular epithelial cells. An extensive investigation of various species from amphibia to mammals showed that the characteristic was common to lower vertebrate, suggesting an important role of IF in VECs. Rat VECs express desmin. In Masugi nephritis, the staining intensity of desmin was parallel with the amount of injected dose of anti-GBM antisera and proteinuria. In puromycin aminonucleoside nephrosis, increase and decrease of the amount of desmin in VECs was shown to be parallel to proteinuria by Western blotting and immunostaining. These findings indicated that desmin expression in VECs was influenced by the condition under stress such as nephrosis. Plectin is an IF-associated protein which is postulated to function as a general cytoplasmic cross-linking element of IFs. Depending on cell types, plectin was found primarily either through the cytoplasm, at the cell periphery, or in the both location. VECs uniquely showed plectin attached predominantly to the perinuclear region. The cytoplasmic staining became intense in puromycine aminonucleoside nephrosis. We hypothesize that abundant IFs and uniquely distributed plectin in VECs function to resist mechanical stress produced by ultrafiltrate from slit diaphragm and pulsing capillary walls.