Project 3: Translational Genomics of Hyperuricemia

项目摘要 慢性肾脏病（CKD）与高尿酸血症（HU）和痛风密切相关;然而， 关系尚不清楚。在全基因组关联研究（GWAS）中确定的>30个尿酸盐基因中，有10个是 也与CKD有关。尿酸盐转运蛋白的遗传变异（例如，SLC 2A 9，编码GLUT 9 转运蛋白）与HU和痛风有关;然而，确切的致病基因及其机制尚不清楚。 不清楚对GLUT 9和其他尿酸盐转运体以及与尿酸盐转运相关的信号网络的调节作用 HU和CKD对于理解HU的功能基因组学及其与CKD的因果关系高度相关。 此外，与非裔美国人CKD遗传风险相关的APOL 1蛋白与 我们的数据提示APOL 1基因型与血清尿酸（sUA）有关。 通过解开HU和CKD之间的分子关系来填补关键的知识空白。因此我们 提出关键的翻译遗传和功能研究，使用尖端的翻译生理学 和遗传学。在目标1中，我们将筛选和表征与这两种疾病有关的调节蛋白（包括APOL 1）。 HU和CKD，以确定与尿酸盐转运的功能相互作用。为了做到这一点，我们将首先检查 在非洲爪蟾卵母细胞中与GLUT 9和其他尿酸盐转运蛋白共表达对尿酸盐转运的影响。这 这种方法已经揭示了双基因TMEM 171/174位点的新生理学， 通过TMEM 171的基底外侧GLUT 9和通过TMEM 174的顶端URAT 1转运。多个重新排序资源 将筛选这些调控基因中不常见的渗透编码变体， 在sUA中;然后将表征这些变体的功能效应。在目标2中，我们提出了最先进的 遗传方法使用非常大的，公开可用的数据集，以发现因果关系和共享的遗传 HU和CKD的病因。确定共同的遗传和/或环境因素的相对重要性， 我们将直接量化基于全基因组标记的遗传和环境因素， 使用多变量贝叶斯全基因组回归（WGR）分析sUA与eGFR/CKD之间的相关性。到 确定共同导致HU和eGFR/CKD的特定基因和途径，我们将估计遗传 使用WGR的基因组区域的相关性。我们将研究尿酸盐升高遗传变异在 肾功能降低;这将通过孟德尔随机化进行正式检验。最后，还有一个重大的未解决问题， 需要一种遗传学上易处理的人尿酸盐稳态模型。我们的团队已经证明人类干细胞- 衍生的肾细胞自组织成人肾类器官， 上皮生理学在目标3中，我们将利用该系统研究CKD和HU相关基因，首先分析 TMEM 171/174基因座中调节SNP的作用以及TMEM 171和TMEM 174在 肾小管尿酸盐生理学该项目的完成将为转化尿酸盐研究提供新的工具， 对CKD和HU中共有途径的新见解，适用于治疗靶向。

PROJECT SUMMARY Chronic kidney disease (CKD) is strongly associated with hyperuricemia (HU) and gout; however, the causal relationship is unclear. Of >30 urate genes identified in genome-wide association studies (GWAS), ten are also associated with CKD. Genetic variation in urate transporters (e.g., SLC2A9, encoding the GLUT9 transporter) has been implicated in HU and gout; however, exact causal genes and their mechanisms are unclear. The regulatory effects on GLUT9 and other urate transporters and signaling networks associated with HU and CKD are highly relevant to understanding the functional genomics of HU and its causality with CKD. Furthermore, APOL1 protein, linked to the genetic risk of CKD in African Americans, is co-expressed with GLUT9, and our data suggest an association of APOL1 genotype on serum urate (sUA).Our goal is to fill these key knowledge gaps by unraveling the molecular relationship between HU and CKD. To achieve this, we propose key translational genetic and functional studies, using cutting-edge translational physiology and genetics. In Aim 1 we will screen and characterize regulatory proteins (including APOL1) implicated in both HU and CKD to identify functional interactions with urate transport. To accomplish this we will first examine the effects on urate transport in co-expression with GLUT9 and other urate transporters in Xenopus oocytes. This approach has already revealed novel physiology for the digenic TMEM171/174 locus, with inhibition of basolateral GLUT9 by TMEM171 and of apical URAT1 transport by TMEM174. Multiple resequencing resources will be screened for uncommon penetrant coding variants in these regulatory genes, segregating with extremes in sUA; functional effects of these variants will then be characterized. In Aim 2 we propose state-of-the-art genetic approaches using very large, publicly available data sets to discover the causality and shared genetic etiology of HU and CKD. To determine the relative importance of shared genetic and/or environmental contributions to HU and CKD, we will quantify directly the genome-wide marker-based genetic and environmental correlation between sUA and eGFR/CKD using multivariate Bayesian whole genome regression (WGR). To ascertain specific genes and pathways jointly contributing to HU and eGFR/CKD we will estimate the genetic correlation in genomic regions using WGR. We will investigate a causal role of urate-raising genetic variants in reduced renal function; this will be formally tested by Mendelian randomization. Finally, there is a major unmet need for a genetically tractable model of human urate homeostasis. Our group has shown that human stem-cell- derived kidney cells self-organize into human kidney organoids that functionally recapitulate tissue-specific epithelial physiology. In Aim 3 we will utilize this system to study CKD- and HU-associated genes, first analyzing the role of a regulatory SNP in the TMEM171/174 locus and the individual roles of TMEM171 and TMEM174 in renal tubular urate physiology. Completion of the project will yield novel tools for translational urate research and novel insight into shared pathways in CKD and HU, suitable for therapeutic targeting.