Nephrotic plasma alters slit diaphragm-dependent signaling and translocates nephrin, podocin, and CD2 associated protein in cultured human podocytes
Nephrotic plasma alters slit diaphragm-dependent signaling and translocates nephrin, podocin, and CD2 associated protein in cultured human podocytes
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DOI：
10.1681/asn.2004030172
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发表时间：
2005-03-01
影响因子：
13.6
通讯作者：
Saleem, MA
中科院分区：
文献类型：
--
作者：
Coward, RJM;Foster, RR;Saleem, MA
足细胞是维持肾小球滤过屏障的关键细胞，并依赖于裂隙隔膜(SD)蛋白newitin、podocin和CD2相关蛋白(CD2AP)发挥最佳功能。测试了正常人血浆和肾病患者血浆对足细胞的影响，特别是对SD复合体的影响。通过使用条件永生化的人足细胞系，首次表明暴露在正常和非肾病人血浆中会导致细胞表面newitin、podocin、CD2AP和肌动蛋白的浓度增加。接下来，比较肾病患者和非肾病患者血浆的影响。当与所有肾病患者血浆(和非人血清对照)接触时，neparin podocin和CD2AP呈胞浆分布；neparin和synaptopodin被选择性下调，通过与非肾病患者血浆共同孵育，可将肾病血浆诱导的neparin重新定位到细胞膜上。此外，肾病患者血浆通过酪氨酸激酶磷酸化介导细胞内钙信号的改变。通过使用neaffin突变的人类细胞系，研究表明，这种对正常血浆的信号和易位反应是依赖neaffin的。这项工作表明，肾病患者血浆似乎缺乏通过足细胞SD复合体发挥作用的因子，而这些因子是维持其生理功能所必需的。
Podocytes are critical in maintaining the filtration barrier of the glomerulus and are dependent on the slit diaphragm (SD) proteins nephrin, podocin, and CD2-associated protein (CD2AP) to function optimally. The effects of normal human plasma and nephrotic plasma on podocytes were tested, focusing particularly on the SD complex. With the use of a conditionally immortalized human podocyte cell line, it first was shown that exposure to normal and non-nephrotic human plasma leads to a concentration of nephrin, podocin, CD2AP, and actin at the cell surface. Next, the effects of plasma from patients with nephrotic conditions to non-nephrotic conditions were compared. When exposed to all nephrotic plasma samples (and a non-human serum control), nephrin podocin and CD2AP assumed a cytoplasmic distribution; nephrin and synaptopodin were selectively downregulated, and the relocation of nephrin induced by nephrotic plasma could be rescued back to the plasma membrane by co-incubation with non-nephrotic plasma. Furthermore, intracellular calcium signaling was altered by nephrotic plasma, which was mediated by tyrosine kinase phosphorylation. With the use of nephrin mutant human cell lines, it was shown that this signaling and translocation response to normal plasma is nephrin dependent. This work demonstrates that nephrotic plasma seems to be deficient in factors that act via the podocyte SD complex, which are essential in maintaining its physiologic function.