Whirlin and PDZ Domain-containing 7 (PDZD7) Proteins Are Both Required to Form the Quaternary Protein Complex Associated with Usher Syndrome Type 2
Whirlin and PDZ Domain-containing 7 (PDZD7) Proteins Are Both Required to Form the Quaternary Protein Complex Associated with Usher Syndrome Type 2
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DOI：
10.1074/jbc.m114.610535
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发表时间：
2014-12-26
影响因子：
4.8
通讯作者：
Yang, Jun
中科院分区：
文献类型：
--
作者：
Chen, Qian;Zou, Junhuang;Yang, Jun
USH综合征(USH)是导致听力和视力丧失的主要遗传原因。在USH的三种临床类型中，以2型(USH2)最常见。USH2A、GPR98和WHRN是USH2的三个已知致病基因，而PDZD7是在USH2患者中发现的修饰基因。这四个USH基因编码的蛋白质被认为形成了一个多蛋白复合体，即USH2复合体，因为在体外发现了这些蛋白质之间的相互作用，它们在体内的共定位，以及这些蛋白质中的一些在体内的正常定位是相互依赖的。然而，还没有证据表明USH2复合体的形成，这个复合体是如何形成的细节仍然难以捉摸。在这里，我们使用共定位、酵母双杂交和下拉试验系统地研究了四种USH蛋白胞内区域之间的相互作用。我们证明了四个USH蛋白的多个结构域相互作用。重要的是，WHRN和PDZD7对于与USH2A和GPR98的复杂地层都是必需的。在这个USH2四元络合物中，WHRN更喜欢与USH2A结合，而PDZD7更喜欢与GPR98结合。WHRN和PDZD7之间的相互作用是USH2A和GPR98之间的桥梁。此外，USH2四元络合物具有可变的化学计量比。这些发现表明，体内可能存在一种非专有的、短期的、动态的USH2四元蛋白复合体。我们的工作为了解USH2复合体在体内的生理作用提供了有价值的见解，并为未来治疗提供了可能的重建USH2复合体的信息。
Usher syndrome (USH) is the leading genetic cause of combined hearing and vision loss. Among the three USH clinical types, type 2 (USH2) occurs most commonly. USH2A, GPR98, and WHRN are three known causative genes of USH2, whereas PDZD7 is a modifier gene found in USH2 patients. The proteins encoded by these four USH genes have been proposed to form a multiprotein complex, the USH2 complex, due to interactions found among some of these proteins in vitro, their colocalization in vivo, and mutual dependence of some of these proteins for their normal in vivo localizations. However, evidence showing the formation of the USH2 complex is missing, and details on how this complex is formed remain elusive. Here, we systematically investigated interactions among the intracellular regions of the four USH proteins using colocalization, yeast two-hybrid, and pull-down assays. We show that multiple domains of the four USH proteins interact among one another. Importantly, both WHRN and PDZD7 are required for the complex formation with USH2A and GPR98. In this USH2 quaternary complex, WHRN prefers to bind to USH2A, whereas PDZD7 prefers to bind to GPR98. Interaction between WHRN and PDZD7 is the bridge between USH2A and GPR98. Additionally, the USH2 quaternary complex has a variable stoichiometry. These findings suggest that a non-obligate, short term, and dynamic USH2 quaternary protein complex may exist in vivo. Our work provides valuable insight into the physiological role of the USH2 complex in vivo and informs possible reconstruction of the USH2 complex for future therapy.