Megalin dependent urinary cystatin C excretion in ischemic kidney injury in rats
Megalin dependent urinary cystatin C excretion in ischemic kidney injury in rats
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DOI：
10.1371/journal.pone.0178796
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发表时间：
2017-06-02
期刊：
影响因子：
3.7
通讯作者：
Birn, Henrik
中科院分区：
文献类型：
--
作者：
Jensen, Danny;Kierulf-Lassen, Casper;Birn, Henrik
胱抑素C是肾损伤的标志物，在肾小球中自由过滤并被近端肾小管重新吸收。meggalin和cubilin是大多数过滤蛋白重吸收所必需的内吞受体。本研究探讨了这些受体对胱抑素C摄取和排泄的作用，并在大鼠模型中探讨了肾缺血/再灌注损伤对肾胱抑素C摄取和排泄的影响。方法采用表面等离子体共振法分析胱抑素C与巨噬细胞苷和立方蛋白的结合。采用ELISA和/或免疫印迹和免疫组织化学方法研究小鼠尿排泄和内源性胱抑素C的小管摄取。此外，研究了缺血/再灌注损伤大鼠肾对胱抑素C的摄取和尿排泄。结果鉴定出胱抑素C与巨噬细胞苷和立方蛋白有高亲和力结合。meggalin缺陷小鼠显示尿中胱抑素C排泄增加，与胞吞摄取缺陷有关。暴露于缺血/再灌注损伤的大鼠尿胱抑素C分泌增加，并伴有近端小管内吞作用的局灶性减少，而meggalin的表达无明显变化。结论megalin对内源性胱抑素C的正常恢复至关重要。缺血/再灌注损伤后尿胱抑素C排泄增加与肾小管摄取减少有关，而与megalin表达减少无关。
BackgroundCystatin C, a marker of kidney injury, is freely filtered in the glomeruli and reabsorbed by the proximal tubules. Megalin and cubilin are endocytic receptors essential for reabsorption of most filtered proteins. This study examines the role of these receptors for the uptake and excretion of cystatin C and explores the effect of renal ischemia/reperfusion injury on renal cystatin C uptake and excretion in a rat model.MethodsBinding of cystatin C to megalin and cubilin was analyzed by surface plasmon resonance analysis. ELISA and/or immunoblotting and immunohistochemistry were used to study the urinary excretion and tubular uptake of endogenous cystatin C in mice. Furthermore, renal uptake and urinary excretion of cystatin C was investigated in rats exposed to ischemia/ reperfusion injury.ResultsA high affinity binding of cystatin C to megalin and cubilin was identified. Megalin deficient mice revealed an increased urinary excretion of cystatin C associated with defective uptake by endocytosis. In rats exposed to ischemia/reperfusion injury urinary cystatin C excretion was increased and associated with a focal decrease in proximal tubule endocytosis with no apparent change in megalin expression.ConclusionsMegalin is essential for the normal tubular recovery of endogenous cystatin C. The increase in urinary cystatin C excretion after ischemia/reperfusion injury is associated with decreased tubular uptake but not with reduced megalin expression.