Novel Wnt effectors in renal cystic disease

描述（由申请人提供）：尽管在鉴定人类遗传疾病潜在突变方面取得了显著进展，但基因型的预测能力仍然很差，部分原因是每位患者的最终临床结果是致病突变和第二位点修饰等位基因之间的上位相互作用以及随机和环境效应的净结果。Bardet-Biedl综合征（BBS）是研究上位性的一个有用的模型;一些研究表明，在12个致病基因中的每一个中，以及在其他转录本中，修饰等位基因，调节疾病的表达率和表达率。BBS还代表了一种模型纤毛病，一组临床上不同但表型重叠的疾病，包括多囊肾病（PKD），肾结核（NPHP），Joubert综合征（JS）和Meckel-Gruber综合征（MKS）。最近的数据表明，纤毛，其锚定结构，基体，所需的传输形态发生的线索，这一过程的失败可能与一些观察到的临床表型，如肾囊肿疾病的因果关系。几种BBS蛋白的功能丧失已被证明会破坏非经典Wnt信号传导，这反过来又与患者和脊椎动物模型中发现的一些囊性表型相关。关注Wnt信号传导对肾脏表型的贡献，我们推断将存在能够通过加重、改善或挽救缺陷性Wnt传递来调节一个BBS位点的功能丧失突变的生化效应的蛋白质。根据定义，编码这些分子的转录物代表了在人类中贡献转录率和表达率修饰等位基因的主要候选者，其鉴定将：a）指数地提高我们对人类遗传负荷的理解; B）促进该病症的临床管理;和c）与其他纤毛病中的肾囊肿疾病的发展潜在相关。为了进一步探索这些可能性，我们建议1）通过利用组合的shRNA、表达载体和发光报告基因来研究新定义的纤毛蛋白质组的约500个成员在BBS突变肾细胞中调节Wnt信号传导反应，和2）通过筛选单倍型的候选基因，探索这些潜在修饰蛋白在调节BBS患者肾表型中的生理相关性与疾病表型相关的标记，并对我们的BBS队列进行修饰等位基因测序。

DESCRIPTION (provided by applicant): Despite the remarkable advances in identifying mutations underlying human genetic disease, the predictive power of the genotype remains poor, in part because the ultimate clinical outcome in each patient is the net result of epistatic interactions between disease causing mutations and second site modifying alleles, as well as stochastic and environmental effects. Bardet-Biedl syndrome (BBS) represents a useful model to study epistasis; several studies have shown that modifying alleles in each of the twelve causative genes, as well as in other transcripts, modulate the penetrance and expressivity of the disorder. BBS also represents a model ciliopathy, an emerging group of clinically distinct but phenotypically overlapping disorders that include polycystic kidney disease (PKD), Nephronophthisis (NPHP), Joubert syndrome (JS) and Meckel-Gruber syndrome (MKS). Recent data have shown that the cilium, and its anchoring structure, the basal body, are required for the transmission morphogenetic cues and that failure of this process can be causally associated with some of the observed clinical phenotypes, such as renal cystic disease. Loss of function of several BBS proteins has been shown to disrupt non-canonical Wnt signaling, which in turn has been associated with some of the cystic phenotypes found in patients and vertebrate animal models. Focusing on the contribution of Wnt signaling to the renal phenotype, we reason that there will be proteins that have the ability to modulate the biochemical effect of loss of function mutations at one BBS locus by either exacerbating, ameliorating, or rescuing defective Wnt transmission. By definition, the transcripts that encode these molecules represent major candidates for contributing penetrance and expressivity modifying alleles in humans, the identification of which will: a) improve exponentially our understanding of genetic load in humans; b) facilitate the clinical management of the disorder; and c) be potentially relevant to the development of renal cystic disease in other ciliopathies. To explore these possibilities further, we propose to 1) investigate ~500 members of the newly defined ciliary proteome in modulating the Wnt signaling response in BBS mutant renal cells by utilizing a combination shRNAs, expression vectors, and luminescent reporters, and 2) explore the physiological relevance of these potential modifier proteins in modulating the renal phenotype of BBS patients by screening candidate genes for a haplotype signature that associates with disease phenotype and sequencing our BBS cohort for modifier alleles.