Immunoglobulin Light Chains Activate Tubular Epithelial Cells through Redox Signaling
Immunoglobulin Light Chains Activate Tubular Epithelial Cells through Redox Signaling
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DOI：
10.1681/asn.2009101089
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发表时间：
2010-07-01
影响因子：
13.6
通讯作者：
Sanders, Paul W.
中科院分区：
文献类型：
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作者：
Basnayake, Kolitha;Ying, Wei-Zhong;Sanders, Paul W.
肾近端小管代谢循环中的低分子量蛋白质，如游离轻链。在浆细胞异常的情况下，过滤蛋白的负担可能非常高。某些肾毒性轻链的内吞作用诱导H2O2的产生和单核细胞化学引诱蛋白-1 （MCP-1）的释放，导致炎症细胞的募集和间质纤维化，但这些过程的机制联系尚不清楚。本研究探讨了人近端小管细胞（HK-2）轻链内吞后产生的H2O2与活化c-Src（一种氧化还原敏感的酪氨酸激酶）之间的关系。暴露于两种不同轻链的HK-2细胞上调c-Src活性，从而增加MCP-1的产生。同时，我们观察到c-Src的氧化随时间变化。抑制c-Src活性和沉默c-Src表达可以消除轻链诱导的MCP-1反应，但对H2O2没有影响，这表明H2O2的产生在信号级联中位于c-Src的上游。沉默meggalin和cubilin的表达会抑制MCP-1的反应，而胞外过氧化氢酶则不会，这表明胞内吞作用是必需的，细胞内活性氧的产生激活了c-Src。这些数据表明单克隆游离轻链内吞诱导的细胞内H2O2氧化并激活c-Src，从而促进MCP-1的释放。
The renal proximal tubule metabolizes circulating low-molecular-weight proteins such as Ig free light chains. In the setting of plasma cell dyscrasias, the burden of filtered protein can be very high. Endocytosis of certain nephrotoxic light chains induces H2O2 production and monocyte chemoattractant protein-1 (MCP-1) release, leading to recruitment of inflammatory cells and interstitial fibrosis, but how these processes are linked mechanistically is not well understood. This study investigated the relationship between H2O2 generated after light chain endocytosis by human proximal tubular (HK-2) cells and activation of c-Src, a redox-sensitive tyrosine kinase. HK-2 cells exposed to two different light chains upregulated c-Src activity, which increased the production of MCP-1. In parallel, we observed a time-dependent oxidation of c-Src. Inhibition of c-Src activity and silencing c-Src expression abrogated the light chain induced MCP-1 response, but had no effect on H2O2, indicating that production of H2O2 is upstream of c-Src in the signaling cascade. Silencing megalin and cubilin expression inhibited the MCP-1 response, whereas extracellular catalase did not, indicating that endocytosis is required and that intracellular generation of reactive oxygen species activates c-Src. These data show that intracellular H2O2 induced by endocytosis of monoclonal free light chains oxidizes and activates c-Src, which promotes release of MCP-1.