PKCα Mediates β-Arrestin2-dependent Nephrin Endocytosis in Hyperglycemia
PKCα Mediates β-Arrestin2-dependent Nephrin Endocytosis in Hyperglycemia
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DOI：
10.1074/jbc.m110.204024
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发表时间：
2011-04-15
影响因子：
4.8
通讯作者：
Sellin, Lorenz
中科院分区：
文献类型：
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作者：
Quack, Ivo;Woznowski, Magdalena;Sellin, Lorenz
去氧肾上腺素是肾小球裂隙隔膜的关键分子，在足细胞表面表达，对于预防蛋白尿至关重要。在糖尿病中，高血糖导致去氧肾上腺素表面表达丧失并引起蛋白尿。在这里，我们报告了一种可以解释这一现象的机制：高血糖通过 PKC α 调节 β-arrestin2-nephrin 相互作用，直接提高去氧肾上腺素内吞速率。我们将 PKC α 和与 c 激酶 1 (PICK1) 相互作用的蛋白鉴定为去氧肾上腺素结合蛋白。高血糖诱导 PKC α 上调，并导致体内外去氧肾上腺素、PKC α、PICK1 和 β-arrestin2 复合物的形成。 β-arrestin2 与去氧肾上腺素胞内结构域的结合取决于去氧肾上腺素苏氨酸残基 1120 和 1125 被 PKC α 磷酸化。此外，PKC α和/或PICK1的细胞敲低减弱了去氧肾上腺素β-arrestin2相互作用，并消除了高血糖对去氧肾上腺素内吞作用的放大作用。在 C57BL/6 小鼠中，超过 24 小时的高血糖导致尿白蛋白排泄显着增加，支持高血糖对肾小球通透性选择性快速影响的概念。总之，我们提供了高血糖诱导的去氧肾上腺素内吞作用和随后的蛋白尿的分子模型，并强调 PKC α 和 PICK1 作为糖尿病肾病有希望的治疗靶点。
Nephrin, the key molecule of the glomerular slit diaphragm, is expressed on the surface of podocytes and is critical in preventing albuminuria. In diabetes, hyperglycemia leads to the loss of surface expression of nephrin and causes albuminuria. Here, we report a mechanism that can explain this phenomenon: hyperglycemia directly enhances the rate of nephrin endocytosis via regulation of the beta-arrestin2-nephrin interaction by PKC alpha. We identified PKC alpha and protein interacting with c kinase-1 (PICK1) as nephrin-binding proteins. Hyperglycemia induced up-regulation of PKC alpha and led to the formation of a complex of nephrin, PKC alpha, PICK1, and beta-arrestin2 in vitro and in vivo. Binding of beta-arrestin2 to the nephrin intracellular domain depended on phosphorylation of nephrin threonine residues 1120 and 1125 by PKC alpha. Further, cellular knockdown of PKC alpha and/or PICK1 attenuated the nephrin beta-arrestin2 interaction and abrogated the amplifying effect of high blood glucose on nephrin endocytosis. In C57BL/6 mice, hyperglycemia over 24 h caused a significant increase in urinary albumin excretion, supporting the concept of the rapid impact of hyperglycemia on glomerular permselectivity. In summary, we have provided a molecular model of hyperglycemia-induced nephrin endocytosis and subsequent proteinuria and highlighted PKC alpha and PICK1 as promising therapeutic targets for diabetic nephropathy.