A Novel Aldehyde Dehydrogenase (ALDH16A1) in Gout

摘要 痛风是炎症性关节炎的一种常见形式，由血液中尿酸浓度升高引起。最近， 全基因组关联研究发现SLC2A9和ABCG2基因是高尿酸血症的主要调节基因 SLC22A12、SLC17A1、ABRB3和MTHFR。然而，这些基因的遗传变异只解释了一小部分 高加索人血清尿酸总变异的比例。最近的一项研究(Nat Genet.43：1127-30,2011)，6,017冰岛人 在乙醛脱氢酶16A1(ALDH16A1)基因中发现a 与痛风(P=1.5×10~(-16))和血尿酸水平(P=4.5×10~(-21))相关。虽然这是一种罕见的SNP，但它的高 关联性强烈暗示了ALDH16A1介导的调节尿酸水平的新途径。ALDH16A1是一种 罕见错义单核苷酸多态(SNP) 从细菌到哺乳动物的所有ALDH16蛋白都含有两个 (而不是一个)ALDH结构域、四个跨膜结构域和一个螺旋线圈结构域。有趣的是，哺乳动物ALDH16 蛋白质缺乏通常催化活性所必需的活性部位的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 ALDH超家族中新颖而又相当独特的成员。 催化功能。ALDH16A1与Maspardin的相互作用就是一个例子，Maspardin是一种与Mast相关的蛋白质 综合症。我们实验室的分子模拟和实验证据表明，人类ALDH16A1与 使用 次黄嘌呤磷酸核糖转移酶1( HPRT1)，一个在嘌呤挽救途径中起关键作用的分子 与之相关的还有尿酸生产。HPRT1活性缺失(Lesch-Nyan综合征)或HPRT1功能降低(Kelley- 西格米勒综合征)会导致高尿酸血症和痛风。我们的初步研究表明，细胞 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。失调症 ALDH16A1的作用可能导致血清尿酸水平升高，并导致以下疾病 高尿酸血症。因此，我们建议：具体目标1.确定人与人之间的蛋白质-蛋白质相互作用 ALDH16A1和HPRT1，并研究这些相互作用的生化意义。具体目标2.调查 ALDH16A1在调节细胞尿酸水平中的作用。完成后，本提案中所取得的成果将 为更详细、更有针对性的R01应用程序奠定基础，旨在彻底了解 ALDH16A1用于痛风，最终目标是预防和治疗这种衰弱的疾病。

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.