A Novel Aldehyde Dehydrogenase (ALDH16A1) in Gout

摘要 痛风是一种常见的炎症性关节炎，是由血液中尿酸浓度升高引起的。最近， 一项全基因组关联研究（GWAS）发现，SLC2A9和ABCG 2基因是高尿酸血症的主要调节因子，沿着 SLC22A12、SLC17A1、ABRB3和MTHFR。然而，这些基因的遗传变异只能解释一小部分 高加索人血清尿酸总变异的百分比。最近的一项研究（Nat Genet. 43：1127 - 30，2011）在6，017名冰岛人中 在乙醛脱氢酶16A1（ALDH16A1）基因中鉴定出一个 与痛风（P = 1.5 x 10 - 16）和血清尿酸水平（P = 4.5 x 10 - 21）相关。虽然这是一个罕见的SNP，但它的高 相关性强烈暗示了一种新的ALDH16A1介导的调节尿酸水平的途径。ALDH16A1是一种 罕见错义单核苷酸多态性 从细菌到哺乳动物的所有ALDH16蛋白都含有两个 一个（而不是一个）ALDH结构域，四个跨膜结构域和卷曲螺旋结构域。有趣的是，哺乳动物ALDH 16 蛋白质缺乏通常催化活性所必需的活性位点Cys-302。我们最近公布的数据显示， 证实了这种催化活性的缺乏。因此，ALDH16A1的任何细胞作用都可能依赖于一些非生物活性物质。 ALDH超家族中新颖而独特的成员。 催化功能这方面的一个例子是ALDH16A1与maspardin的相互作用，maspardin是一种与肥大细胞相关的蛋白质。 综合征我们实验室的分子模型和实验证据表明，人ALDH16A1与人ALDH16A1相互作用， 与 次黄嘌呤磷酸核糖基转移酶1（ HPRT 1），一种在嘌呤补救途径中起关键作用的分子 以及相关的尿酸产生。HPRT 1活性缺失（Lesch-Nyan综合征）或HPRT 1功能降低（Kelley- Seegmiller综合征）已知会引起高尿酸血症和痛风。我们的初步研究表明， ALDH16A1导致细胞尿酸水平降低。基于这些数据，我们的工作假设是ALDH16A1 通过蛋白质-蛋白质相互作用增强HPRT1活性来调节尿酸水平。失调 ALDH16A1的作用可能导致血清尿酸水平升高，并导致包括 高尿酸血症因此，我们建议：具体目标1。确认人与人之间的蛋白质相互作用 ALDH16A1和HPRT1，并研究这种相互作用的生化意义。具体目标2。探讨 ALDH16A1在调节细胞尿酸水平中的作用。完成后，本提案所取得的成果将 为更详细、更有针对性的R01应用程序奠定基础， ALDH16A1在痛风中的作用，最终目的是预防和治疗这种使人衰弱的疾病。

Abstract Gout, a common form of inflammatory arthritis, results from elevated uric acid concentrations in the blood. Recently, genome-wide association studies (GWAS) identified SLC2A9 and ABCG2 genes as major regulators of hyperuricemia along with SLC22A12, SLC17A1, ABRB3 and MTHFR. However, genetic variation in these genes explains only a small proportion of the total variation in serum uric acid in Caucasians. A recent study (Nat Genet. 43:1127-30, 2011) in 6,017 Icelanders identified a in the aldehyde dehydrogenase 16A1 (ALDH16A1) gene to be associated with gout (P = 1.5 x 10-16) and serum uric acid levels (P = 4.5 x 10-21). Although this is a rare SNP, its high association is strongly suggestive of a novel ALDH16A1-mediated pathway of regulating uric acid levels. ALDH16A1 is a rare missense single nucleotide polymorphism (SNP) All ALDH16 proteins from bacteria to mammals contain two (rather than one) ALDH domains, four transmembrane domains and a coiled-coil domain. Interestingly, mammalian ALDH16 proteins lack the Cys-302 of the active site that is normally necessary for catalytic activity. Our recently published data have confirmed this lack of catalytic activity. Accordingly, any cellular actions of ALDH16A1 are likely to rely on some non- novel and rather unique member of the ALDH superfamily. catalytic functionality. An example of this is the interaction of ALDH16A1 with maspardin, a protein associated with Mast syndrome. Molecular modeling and experimental evidence from our laboratory suggests that human ALDH16A1 interacts with hypoxanthine phosphoribosyltransferase 1 ( HPRT1), a molecule that plays a key role in the purine salvage pathway and, relatedly, uric acid production. Absence of HPRT1 activity (Lesch-Nyan syndrome) or reduced HPRT1 function (Kelley- Seegmiller syndrome) are known to cause hyperuricemia and gout. Our preliminary studies show that increased cellular ALDH16A1 results in reduced cellular uric acid levels. Based upon these data, our working hypothesis is that ALDH16A1 modulates uric acid levels by enhancing HPRT1 activity through a protein-protein interaction. Dysregulation of the effects of ALDH16A1 could lead to increased serum uric acid levels and contribute to diseases involving hyperuricemia. Accordingly, we propose to:Specific Aim 1. Confirm the protein-protein interactions between human ALDH16A1 and HPRT1 and investigate the biochemical implications of such interactions. Specific Aim 2. Investigate the role of ALDH16A1 in modulating cellular uric acid levels. When completed, the results obtained in the present proposal will lay the groundwork for a more detailed and focused R01 application aimed at thoroughly understanding the role of ALDH16A1 in gout, with the ultimate goal of preventing and treating this debilitating disease.