Snail, a transcriptional regulator, represses nephrin expression in glomerular epithelial cells of nephrotic rats
Snail, a transcriptional regulator, represses nephrin expression in glomerular epithelial cells of nephrotic rats
复制标题
DOI：
10.1038/labinvest.3700518
复制
发表时间：
2007-03-01
影响因子：
5
通讯作者：
Hori, Masatsugu
中科院分区：
文献类型：
--
作者：
Matsui, Isao;Ito, Takahito;Hori, Masatsugu
Snail 是一种 DNA 结合分子，在调节细胞粘附和上皮间质转化中发挥着关键作用。肾小球中的内脏上皮细胞（足细胞）形成一种复杂的细胞-细胞连接，称为狭缝隔膜，可防止超滤过程中血浆蛋白的损失。去氧肾上腺素位于裂隙隔膜中，对于维持该结构的完整性至关重要，属于免疫球蛋白超家族的细胞粘附分子。如先前报道，去氧肾上腺素的转录活性是嘌呤霉素氨基核苷（PAN）肾病大鼠裂隙隔膜完整性的决定因素。在这里，我们研究了 Snail 在去氧肾上腺素表达中的作用。与 PAN 肾病大鼠中去氧肾上腺素的下调一致，Snail 在体内表达上调，并且其 DNA 结合活性在受损的足细胞中受到刺激，而正常足细胞不表达 Snail。一项体外研究表明，Snail 与大鼠去氧肾上腺素基因特定片段中的 E-box 基序结合，可抑制去氧肾上腺素的转录并下调去氧肾上腺素蛋白。我们还发现受损足细胞中 Snail 的表达水平受到 GSK3 的调节，已知 GSK3 可以磷酸化 Snail 并诱导其蛋白水解。 GSK3 的体外和体内药理学抑制研究表明，受损的足细胞中 GSK3 活性降低，这种变化部分导致去氧肾上腺素减少以及 Snail 和蛋白尿增加。一致地，我们发现 Wnt-2 在受损的足细胞中上调并激活了令状经典途径。由于令状经典途径使 GSK3 失活，因此 Wnt-2 很可能是 Snail 在受损足细胞中积累的原因。总之，Snail 是一种关键分子，在病理条件下通过去氧肾上腺素的转录抑制来扰乱裂隙隔膜的完整性。 Wnt-GSK3 通路参与了这一机制。
Snail is a DNA-binding molecule that plays a pivotal role in regulating cell adhesion and epithelial to mesenchymal transition. Visceral epithelial cells (podocytes) in kidney glomeruli form a sophisticated cell-cell junction called a slit diaphragm that prevents the loss of plasma protein during ultrafiltration. Nephrin, located in the slit diaphragm and critical for maintaining the integrity of this structure, belongs to the class of cell adhesion molecules of the immunoglobulin super-family. As previously reported, the transcriptional activity of nephrin is a determinant of the integrity of the slit diaphragm in puromycin aminonucleoside (PAN) nephrosis rats. Here, we examined the role of Snail in nephrin expression. In accordance with the downregulation of nephrin in PAN nephrosis rats, Snail was upregulated in vivo and its DNA-binding activity was stimulated in injured podocytes while normal podocytes did not express Snail. An in vitro study demonstrated that Snail bound to E-box motifs in a specific segment of the rat nephrin gene repressed the transcription of nephrin and downregulated nephrin protein. We also found that the expression level of Snail in injured podocytes was regulated by GSK3, which is known to phosphorylate Snail and induce its proteolysis. Pharmacological in vitro and in vivo inhibition studies of GSK3 suggested that GSK3 activity decreased in injured podocytes and this change partially contributed to the decrease in nephrin and increase in Snail and proteinuria. Concordantly, we found that Wnt-2 was upregulated in injured podocytes and activated the Writ canonical pathway. As the Writ canonical pathway inactivates GSK3, it is likely that Wnt-2 accounts for the accumulation of Snail in injured podocytes. In conclusion, Snail is a key molecule, which perturbs the integrity of the slit diaphragm through transcriptional repression of nephrin under pathological conditions. Wnt-GSK3 pathway participates in this mechanism.