A Model for Nephronophthisis in Caenorhabditis elegans

描述(申请人提供)：肾炎是一种常染色体隐性遗传性肾脏疾病，是儿童和年轻人终末期肾脏疾病最常见的遗传原因。肾炎是由至少五个基因之一的突变引起的，即NPHP1-NPHP5。NPHP、常染色体显性遗传性多囊肾病(ADPKD)和其他人类囊性肾脏疾病都与纤毛缺陷有关。NPHP蛋白产物(肾囊素)定位于纤毛，但对这些重要蛋白的细胞和分子功能几乎一无所知。线虫秀丽线虫在研究其天然细胞环境中肾囊毒素的生理作用方面具有显著的实验优势。我们已经开发并建立了蠕虫作为NPHP的模型。我们发现nphp-1和nphp-4在纤毛感觉神经系统中表达，并与线虫ADPKD基因lov-1/pC-1和pKD-2/pC-2共表达。与人类肾囊蛋白类似，GFP标记的NPHP-1和NPHP-4蛋白定位于纤毛。与感觉作用一致的是，我们发现nphp-1和nphp-4缺失突变体形成纤毛，但在一些感觉行为上存在缺陷，包括雄性交配和Dauer形成。我们提出并将测试三种模型的肾囊藻毒素功能。在第一种模型中，肾囊蛋白起结构性作用，调节纤毛的发育或形态发生。在第二种模型中，肾囊素在纤毛蛋白运输中起作用。在最后的模型中，肾囊蛋白在纤毛内或纤毛外的感觉转导中起信号传递的作用。纤毛定位的NPHP和ADPKD蛋白具有高度的物种保守性，这使得这些对线虫的研究可能有助于阐明正常和病理疾病状态下肾囊素在人类肾脏中的作用。这一建议的结果将为几个领域提供有价值的见解，包括肾囊蛋白的功能、蛋白质运输、感觉信号转导和人类睫状结构疾病。

DESCRIPTION (provided by applicant): Nephronophthisis is an autosomal recessive kidney disease and the most common genetic cause of end-stage renal disease in children and young adults. Nephronophthisis is caused by mutation in one of at least five genes, NPHP1 - NPHP5. NPHP, autosomal dominant polycystic kidney disease (ADPKD) and other human cystic kidney diseases have been associated with defects in cilia. The NPHP protein products (the nephrocystins) localize to cilia, but almost nothing is known about the cellular and molecular functions of these important proteins. The nematode Caenorhabditis elegans offers significant experimental advantages for characterizing the physiological roles of the nephrocystins in their native cellular environments. We have developed and established the worm as a model for NPHP. We showed that nphp-1 and nphp-4 are expressed in ciliated sensory nervous system and are coexpressed with the C. elegans ADPKD genes lov-1/PC-1 and pkd-2/PC-2. Similar to the human nephrocystins, GFP-tagged NPHP-1 and NPHP-4 proteins localize to cilia. Consistent with a role in sensation, we found that nphp-1 and nphp-4 deletion mutants form cilia but are defective in several sensory behaviors, including male mating and dauer formation. We propose and will test three models for nephrocystin function. In the first model, the nephrocystins play a structural role and regulate cilia development or morphogenesis. In the second model, the nephrocystins function in ciliary protein transport. In the final model, the nephrocystins act in a signaling capacity to mediate sensory transduction within or from the cilium. The high level of species conservation of ciliary-localized NPHP and ADPKD proteins makes it likely that these studies in C. elegans will help elucidate how the nephrocystins work in the human kidney in normal and pathological disease states. The results of this proposal will provide valuable insight into several areas, including the functions of the nephrocystins, protein transport, sensory signaling transduction, and human ciliary diseases.