Altered trafficking and stability of polycystins underlie polycystic kidney disease
Altered trafficking and stability of polycystins underlie polycystic kidney disease
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DOI：
10.1172/jci67273
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发表时间：
2014-12-01
影响因子：
15.9
通讯作者：
Somlo, Stefan
中科院分区：
文献类型：
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作者：
Cai, Yiqiang;Fedeles, Sorin V.;Somlo, Stefan
最严重的常染色体显性多囊肾病发生在编码多囊蛋白-1（PC 1）的基因（PKD 1）突变的患者中。PC 1是在纤毛中表达的复杂的多位膜蛋白，其在G蛋白偶联受体蛋白水解位点（GPS）处经历自身蛋白水解裂解。四分之一的PKD 1突变是错义突变，尽管目前尚不清楚这些突变如何促进疾病。在这里，我们建立了一个基于细胞的系统来评估这些突变，并确定PC 1运输到纤毛需要GPS切割。致病性错义突变的一个子集之间的一个共同特征是所导致的失败的PC 1交通纤毛，无论GPS裂解。我们的系统的应用还确定了一个错义突变的基因编码的多囊蛋白-2（PC 2），阻止这种蛋白质正确运输到纤毛。使用Pkd 1-BAC重组工程方法，我们开发了小鼠模型来研究这些突变的影响，并证实只有切割形式的PC 1退出ER，可以挽救胚胎致死的Pkd 1无效突变。此外，稳态表达水平的膜内COOH-末端片段裂解的PC 1需要一个完整的相互作用与PC 2。本研究的结果表明，PC 1的运输和表达需要GPS切割和PC 2的相互作用，分别，并提供了一个框架的功能测定分类的错义突变的影响多囊蛋白。
The most severe form of autosomal dominant polycystic kidney disease occurs in patients with mutations in the gene (PKD1) encoding polycystin-1 (PC1). PC1 is a complex polytopic membrane protein expressed in cilia that undergoes autoproteolytic cleavage at a G protein-coupled receptor proteolytic site (GPS). A quarter of PKD1 mutations are missense variants, though it is not clear how these mutations promote disease. Here, we established a cell-based system to evaluate these mutations and determined that GPS cleavage is required for PC1 trafficking to cilia. A common feature among a subset of pathogenic missense mutations is a resulting failure of PC1 to traffic to cilia regardless of GPS cleavage. The application of our system also identified a missense mutation in the gene encoding polycystin-2 (PC2) that prevented this protein from properly trafficking to cilia. Using a Pkd1-BAC recombineering approach, we developed murine models to study the effects of these mutations and confirmed that only the cleaved form of PC1 exits the ER and can rescue the embryonically lethal Pkd1-null mutation. Additionally, steady-state expression levels of the intramembranous COOH-terminal fragment of cleaved PC1 required an intact interaction with PC2. The results of this study demonstrate that PC1 trafficking and expression require GPS cleavage and PC2 interaction, respectively, and provide a framework for functional assays to categorize the effects of missense mutations in polycystins.