Defective intracellular trafficking of uromodulin mutant isoforms
Defective intracellular trafficking of uromodulin mutant isoforms
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DOI：
10.1111/j.1600-0854.2006.00481.x
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发表时间：
2006-11-01
期刊：
影响因子：
4.5
通讯作者：
Rampoldi, Luca
中科院分区：
文献类型：
--
作者：
Bernascone, Ilenia;Vavassori, Stefano;Rampoldi, Luca
髓质囊性肾病/家族性少年高尿酸血症肾病（MCKD/FJHN）是常染色体显性肾病，以小管间质纤维化、高尿酸血症和髓质囊肿为特征。它们是由编码尿调蛋白的基因突变引起的，尿调蛋白是尿液中含量最多的蛋白质。尿调蛋白（又称Tamm-Horsfall蛋白）是一种糖蛋白，仅由Henle’s袢厚升肢上皮小管细胞和远曲小管表达。迄今为止，在MCKD/FJHN患者中已经发现了37种不同的尿调蛋白突变。有趣的是，其中60%涉及48个保守半胱氨酸残基中的一个。我们以前已经表明，影响半胱氨酸的突变可能导致部分内质网（ER）保留。在这项研究中，为了进一步了解尿调素在健康和疾病中的生物学作用，我们首次对野生型和突变型尿调素亚型的细胞内转运和亚细胞定位进行了广泛的研究。我们分析了一组12种不同的尿调素突变，这些突变代表了迄今为止通过不同的实验方法（免疫荧光、电子显微镜、生物化学和体内成像）在瞬时转染的HEK293和Madin-Darby犬肾细胞中发现的不同类型的突变。我们评估了分泌途径中的蛋白质加工过程，并可以证明，尽管在不同程度上，所有尿调蛋白突变都会导致内质网到高尔基体蛋白运输的缺陷，这表明MCKD/FJHN有一个共同的发病机制。
Medullary cystic kidney disease/familial juvenile hyperuricemic nephropathy (MCKD/FJHN) are autosomal dominant renal disorders characterized by tubulo-interstitial fibrosis, hyperuricemia and medullary cysts. They are caused by mutations in the gene encoding uromodulin, the most abundant protein in urine. Uromodulin (or Tamm-Horsfall protein) is a glycoprotein that is exclusively expressed by epithelial tubular cells of the thick ascending limb of Henle's loop and distal convoluted tubule. To date, 37 different uromodulin mutations have been described in patients with MCKD/FJHN. Interestingly, 60% of them involve one of the 48 conserved cysteine residues. We have previously shown that cysteine-affecting mutations could lead to partial endoplasmic reticulum (ER) retention. In this study, as a further step in understanding uromodulin biology in health and disease, we provide the first extensive study of intracellular trafficking and subcellular localization of wild-type and mutant uromodulin isoforms. We analyzed a set of 12 different uromodulin mutations that were representative of the different kind of mutations identified so far by different experimental approaches (immunofluorescence, electron microscopy, biochemistry and in vivo imaging) in transiently transfected HEK293 and Madin-Darby canine kidney cells. We assessed protein processing in the secretory pathway and could demonstrate that although to different extent, all uromodulin mutations lead to defective ER to Golgi protein transport, suggesting a common pathogenetic mechanism in MCKD/FJHN.