Mitochondrial Metabolism in Primary Hyperoxaluria

原发性高草酸尿症的线粒体代谢

基本信息

批准号：
8926129
负责人：
ROSS P HOLMES
金额：
$ 5.85万
依托单位：
UNIVERSITY OF ALABAMA AT BIRMINGHAM
依托单位国家：
美国
项目类别：
财政年份：
2014
资助国家：
美国
起止时间：
2014-09-16 至 2017-12-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8926129
关键词：
Address Alanine-glyoxylate aminotransferase Alcohols Aldehyde-Lyases Anions Antioxidants Back Bioenergetics Calcium Oxalate Cells Chinese Hamster Ovary Cell Culture Media Cultured Cells Cytoplasm Cytosol Degradation Pathway Diabetes Mellitus Disease End stage renal failure Enzymes Excretory function Experimental Animal Model Fatty Liver Functional disorder Generations Glycolates Glyoxylates Health Heart Diseases Hepatocyte Hereditary Disease Hydrogen Peroxide Hydroxyproline Impairment Individual Infant Infusion procedures Ions Kidney Kidney Calculi Kidney Failure Kidney Transplantation Knockout Mice Knowledge Label Lead Life Liver Measures Metabolic Metabolic Diseases Metabolism Mitochondria Modeling Mus Nephrocalcinosis Oxalates Oxidases Parkinson Disease Pathway interactions Patients Pharmaceutical Preparations Phenotype Plasma Play Primary Hyperoxaluria Process Production Property Proximal Kidney Tubules Rare Diseases Reactive Oxygen Species Renal function Research Rodent Model Role Sampling Source Stress Techniques Testing Therapeutic Tissues Tracer Transplantation Urine Wild Type Mouse alpha ketoglutarate design enzyme activity glyoxylate glyoxylate reductase insight mitochondrial dysfunction mouse model nervous system disorder novel novel strategies oxidation peroxisome pyridoxine research study response urinary

项目摘要

DESCRIPTION (provided by applicant): Primary Hyperoxaluria (PH) is a rare, genetic disorder that is characterized by an increased urinary oxalate excretion, the formation of calcium oxalate kidney stones, and in severe cases renal failure. In the most extreme cases, some develop nephrocalcinosis and renal failure as infants with a poor survival outlook. Our research suggests that hydroxyproline metabolism makes a major contribution to the increased oxalate synthesis that occurs in PH. This metabolism occurs in the mitochondrion and is aberrant in a recently identified form of the disease, Type 3, where the activity of the enzyme, 4-hydroxy-2-oxoglutarate aldolase (HOGA), a component of the degradation pathway, is deficient. A deficiency in another mitochondrial enzyme, glyoxylate reductase, is associated with Type 2 disease. In Type 1 disease, glycolate-glyoxylate cycling occurs in the liver when glycolate produced in mitochondria from hydroxyproline metabolism is oxidized in peroxisomes to glyoxylate and reduced back to glycolate in the cytoplasm because of the absence of AGT. We hypothesize that the hydrogen peroxide produced with this cycling contributes to mitochondrial dysfunction due to an increased generation of reactive oxygen species. We further hypothesize that the altered metabolism in these types of PH may result in an altered concentration of oxalate, glyoxylate and glycolate in mitochondria and the cytosol. Changes in ion levels, particularly oxalate and calcium, could further modify mitochondrial properties. In this proposal, we will use genetically modified mice to determine how the changes in enzyme composition associated with PH alter mitochondrial properties in hepatocytes and renal proximal tubule cells (RPTC). The first specific aim will determine the phenotype of Hoga1 knock-out mice and examine how the substrate, HOG, is split when HOGA is absent. We hypothesize that an alternative aldolase is able to split HOG when its concentration increases sufficiently. The second specific aim will examine mitochondrial properties and metabolic changes that occur in intact hepatocytes and RTPC from normal and genetically modified mice using an XF-analyzer. Mitochondrial quality will also be assessed in liver and kidney tissue of the mouse models and in liver tissue from PH patients receiving a transplant. Whether a mitochondrial specific drug such as MitoQ can offset any adverse changes will be investigated. The third specific aim will identify changes that occur in mitochondria isolated from these mice when they metabolize hydroxyproline and glyoxylate. These experiments will illuminate the metabolism associated with the increased oxalate synthesis that occurs in PH, highlight the role played by mitochondria in the disease process, and illustrate important differences between liver and kidney mitochondria. This research should lead to novel approaches to decrease excessive oxalate synthesis and modify mitochondrial dysfunction in PH.

描述（由申请人提供）：原发性高黄油（pH）是一种罕见的遗传疾病，其特征在于草酸盐排泄增加，草酸钙肾结石的形成以及在严重的情况下肾衰竭。在最极端的情况下，有些人由于生存前景差而出现肾上腺素病和肾衰竭。我们的研究表明，羟丙基代谢对在pH中发生的草酸盐合成增加做出了重大贡献。这种新陈代谢发生在线粒体中，以3型疾病的最近鉴定的形式异常，其中酶的活性，4-羟基-2-氧化醛酸醛酸醛酸酶（HOGA）（HOGA）（降解途径的一种成分）是缺陷的。另一种线粒体酶的缺乏，乙二醇还原酶与2型疾病有关。在1型疾病中，当通过羟基丙烯的代谢在线粒体中产生的乙二醇在过氧化物酶体中氧化以乙二醇化并降低乙二醇化的乙醇糖酸酯循环在肝脏中发生。我们假设用这种循环产生的过氧化氢由于活性氧的产生增加而导致线粒体功能障碍。我们进一步假设，这些类型的pH值的新陈代谢改变可能会导致黄酸盐，乙二醇和乙醇酸酯在线粒体和细胞质中的浓度改变。离子水平的变化，尤其是草酸盐和钙可以进一步改变线粒体特性。在此提案中，我们将使用遗传修饰的小鼠来确定与pH相关的酶组成的变化如何改变肝细胞和肾近端小管细胞（RPTC）中的线粒体特性。第一个特定的目的将确定HOGA1敲除小鼠的表型，并检查hoga不存在HOGA时的底物如何分裂。我们假设替代醛糖酶在其浓度足够增加时能够拆分猪。第二个特定目的将检查使用XF-Analyzer从正常和转基因小鼠中完整的肝细胞和RTPC中发生的线粒体特性和代谢变化。线粒体质量也将在小鼠模型的肝脏和肾脏组织以及接受移植的pH患者的肝组织中进行评估。线粒体特异性药物（例如mitoq）是否可以抵消任何不利变化。第三个特定的目的将确定当这些小鼠代谢羟基丙烯和乙二醇化时从这些小鼠分离的线粒体中发生的变化。这些实验将阐明与pH中发生的草酸盐合成有关的代谢，强调了线粒体在疾病过程中所起的作用，并说明了肝脏和肾脏线粒体之间的重要差异。这项研究应导致新的方法减少草酸盐合成并改变pH中的线粒体功能障碍。