Hydroxproline Catabolism and Hyperoxaluria

羟脯氨酸分解代谢和高草酸尿症

• 批准号: 8075595
• 负责人: ROSS P HOLMES
• 金额: $ 27.03万
• 依托单位: WAKE FOREST UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-06-01 至 2013-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8075595
• 关键词: Alanine-glyoxylate aminotransferase; Animals; Benchmarking; Calcium Oxalate; Catabolism; Collagen; Coupled; Data; Defect; Degradation Pathway; Deposition; Detection; Diet; Enzymes; Excretory function; Exhibits; Foundations; Future; Gelatin; Genetic; Glycine; Glycolates; Glyoxylates; Human; Hydroxyproline; Hyperoxaluria; Intravenous infusion procedures; Kidney; Kidney Calculi; Kidney Failure; Knock-in Mouse; Knock-out; Knockout Mice; Label; Lead; Metabolic; Metabolism; Modeling; Monitor; Mus; Oxalates; Pathway interactions; Patients; Perfusion; Primary Hyperoxaluria; Production; Proteins; Research; Role; Source; Techniques; Testing; Therapeutic; Tracer; glyoxylate; glyoxylate reductase; human subject; innovation; mouse model; public health relevance; research study; therapeutic target; treatment strategy; urinary

DESCRIPTION (provided by applicant): Primary hyperoxaluria types I and 2 (PH1 and PH2) are characterized by an inability to efficiently metabolize glyoxylate as a consequence of functional defects in alanine-glyoxylate aminotransferase and glyoxylate reductase, respectively. Excessive oxalate synthesis results and may ultimately cause renal failure. To date, there are no therapies that can specifically reduce oxalate synthesis. Hydroxyproline metabolism is the only recognized source of glyoxylate that has been identified to date. We hypothesize that the breakdown of dietary and endogenous hydroxyproline contributes to the bulk of the oxalate synthesized in PH1 and PH2 patients. Confirmation of this hypothesis would suggest that the inhibition of hydroxyproline degradation may be a significant therapeutic opportunity for diminishing endogenous oxalate production in PH patients. As a first step toward testing this hypothesis, we have synthesized homogeneously labeled 13C-hydroxyproline and verified that it can be used to follow the degradation of hydroxyproline to oxalate, glycolate, lactate, and glycine using chromatographic techniques coupled to mass detection. The specific aims of the proposed research are: (1) to quantitate the contribution of hydroxyproline metabolism to endogenous oxalate synthesis in normal human subjects and patients with PH using homogeneously-labeled Hyp, 13C5-hydroxyproline, as a metabolic tracer; (2) to quantitate the contribution of hydroxyproline metabolism to endogenous oxalate synthesis in mouse KO models of PH (Agxt and Grhpr KO) using 13C5-hydroxyproline. Through the quantitation and tracking of the isotopic label within metabolites, we will be able to demonstrate whether or not hydroxyproline degradation contributes to endogenous glycolate, and oxalate synthesis. Moreover, the mouse data will benchmark the contribution of hydroxyproline to urinary glycolate and oxalate in each genetic setting. This latter data will be invaluable for the future testing of therapeutics targeting the unique enzymes of the hydroxyproline degradation pathway. PUBLIC HEALTH RELEVANCE: The synthesis of oxalate, a key component of kidney stones, is influenced by glyoxylate levels. Glyoxylate is produced from hydroxyproline during the normal degradation of collagen within the body and that consumed in the diet. The purpose of this study is to determine whether or not hydroxyproline degradation contributes adversely to the elevated levels of glyoxylate and oxalate production observed in primary hyperoxaluria patients.

描述(申请人提供)：原发性高草酸尿症I型和2型(PH1和PH2)的特征是由于丙氨酸-乙氧基酸氨基转移酶和乙氧基酸还原酶功能缺陷而无法有效代谢乙醛。草酸合成过多会导致最终导致肾功能衰竭。到目前为止，还没有专门减少草酸合成的疗法。羟脯氨酸代谢是迄今为止唯一已被确认的乙氧基酸来源。我们假设，在PH1和PH2患者中，膳食和内源性羟脯氨酸的分解是草酸合成的主要原因。这一假说的证实将表明，抑制羟脯氨酸降解可能是减少PH患者内源性草酸产生的重要治疗机会。作为验证这一假说的第一步，我们已经合成了均相标记的13C-羟基脯氨酸，并验证了它可以用来跟踪羟基脯氨酸降解为草酸、乙醇酸、乳酸和甘氨酸的过程，使用与质量检测相结合的色谱技术。这项研究的具体目的是：(1)使用均相标记的Hyp，13C5-羟脯氨酸作为代谢示踪剂，定量研究正常人和PH患者羟脯氨酸代谢对内源性草酸合成的贡献；(2)使用13C5-羟脯氨酸定量研究PHKO模型(Agxt和Grhpr KO)中羟脯氨酸代谢对内源性草酸合成的贡献。通过对代谢物中同位素标记的定量和跟踪，我们将能够证明羟脯氨酸降解是否有助于内源性乙醇酸和草酸的合成。此外，小鼠的数据将基准羟脯氨酸对尿乙醇酸和草酸在每个遗传环境中的贡献。后一项数据将对未来针对羟脯氨酸降解途径的独特酶的疗法测试具有非常重要的价值。 公共卫生相关性：草酸的合成是肾结石的关键成分，它的合成受到乙醛水平的影响。乙醛是在体内胶原蛋白正常降解的过程中由羟基脯氨酸产生的，并在饮食中消耗。这项研究的目的是确定羟脯氨酸降解是否对观察到的原发性高草酸尿症患者乙醛酸和草酸产生水平的升高有不利影响。