Developmental Pharmacology of cytosolic and mitochondrial GSTZ1-1/MAAI

细胞质和线粒体 GSTZ1-1/MAAI 的发育药理学

• 批准号: 8658108
• 负责人: Margaret Olive James
• 金额: $ 32.5万
• 依托单位: UNIVERSITY OF FLORIDA
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2016-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8658108
• 关键词: Acids; Adult; Adverse effects; Affect; Age; Anions; Antineoplastic Agents; Catabolism; Child; Chloride Ion; Chlorides; Chronic; Clinical; Cytosol; Decarboxylation; Development; Dichloroacetate; Dichloroacetic Acid; Disease; Dose; Drug Kinetics; Environmental Exposure; Enzymes; Exhibits; Exposure to; Genetic; Genotype; Glutathione S-Transferase; Glyoxylates; Goals; Half-Life; Haplotypes; Hepatic; Hepatocyte; Heterozygote; Hour; Human; In Vitro; Individual; Lactic Acidosis; Link; Liver; Liver Mitochondria; Location; Longevity; Maleylacetoacetate isomerase; Measurement; Measures; Mediating; Metabolic; Metabolic Biotransformation; Metabolism; Mitochondria; Mitochondrial Matrix; Mutation; Nature; Oxidoreductase; PDH kinase; Peripheral Nervous System Diseases; Persons; Pharmaceutical Preparations; Pharmacodynamics; Pharmacology; Phosphotransferases; Physiological; Play; Process; Property; Proteins; Rattus; Recombinants; Relative (related person); Reporting; Research; Role; Site; Solid Neoplasm; Therapeutic; Therapeutic Effect; Therapeutic Uses; Time; Toxic effect; Translating; Tyrosine; Tyrosine Metabolism Pathway; Variant; Work; adduct; age related; dechlorination; dehalogenation; drinking water; environmental chemical; enzyme activity; fumarylacetone; glyoxylate; in vivo; maleylacetone; protein expression; pulmonary arterial hypertension; response; therapeutic target

DESCRIPTION (provided by applicant): The broad, long-term objectives of this research are to understand the properties of glutathione transferase Z1- 1 (GSTZ1-1) and its role in the elimination of haloacetic acids, particularly dichloroacetic acid (DCA) across the human lifespan. This is important because while DCA has therapeutic benefits in treating certain solid tumors, lactic acidosis and pulmonary arterial hypertension, it exhibits marked individual variability in pharmacokinetics, and can cause side effects at high doses, particularly in adults. The first step in DCA metabolism is dechlorination to glyoxylate, catalyzed by GSTZ1-1. Also known as maleylacetoacetate isomerase, and playing an important role in catabolism of tyrosine, GSTZ1-1 is expressed mainly in the liver and is the only enzyme known to catalyze the dehalogenation of haloacetic acids, including DCA. Although it is well recognized that DCA inhibits its own metabolism and the metabolism of maleylacetoacetate and its decarboxylation product, maleylacetone, almost certainly because DCA inactivates GSTZ1-1, the reasons for the marked individual variability in pharmacokinetics of DCA after repeated doses are only beginning to be understood. Most adults clear repeated doses of DCA more slowly than most children. Persons with different GSTZ1-1 haplotypes appear to differ in their response to repeated doses of DCA. Recent in vitro work showed that chloride concentration affected the rate of inactivation of GSTZ1-1 by DCA in a haplotype-dependent manner. In addition to its well-known presence in liver cytosol, GSTZ1-1 has recently been found to exist in the mitochondrial matrix. This is the same location as pyruvate dehydrogenase kinase, DCA's pharmacodynamics site of action. Most of the downstream metabolism of the DCA metabolite, glyoxylate, occurs in the mitochondria suggesting the importance of this site in the overall disposition of DCA. This application seeks to examine age-related changes in expression and activity of GSTZ1-1 across the human lifespan and ascertain the properties of the newly-discovered mitochondrial enzyme. Three specific aims are proposed. The first specific aim will investigate age-related changes in hepatic GSTZ1-1 expression and activity in mitochondria and cytosol. The second specific aim will examine the properties of the mitochondrial enzyme, with respect to the relative loss of mitochondrial versus cytosolic GSTZ1-1 following in vivo exposure to DCA, and the ability of the mitochondrial GSTZ1-1/MAAI to convert the physiologically important substrate of GSTZ1-1, maleylacetone, to fumarylacetone. The third specific aim will use in vitro studies to investigate sensitivity of mitochondrial GSTZ1-1 to inactivation by DCA and the role of chloride and haplotype as determinants of the rate and mechanism of inactivation of cytosolic, mitochondrial and expressed GSTZ1-1 by DCA.

描述（由申请人提供）：本研究的广泛、长期目标是了解谷胱甘肽转移酶Z1- 1（GSTZ 1 -1）的特性及其在人类寿命期间消除卤代乙酸（特别是二氯乙酸（DCA））的作用。这一点很重要，因为虽然DCA在治疗某些实体瘤、乳酸性酸中毒和肺动脉高压方面具有治疗益处，但它在药代动力学方面表现出明显的个体差异，并且在高剂量时可能引起副作用，特别是在成人中。DCA代谢的第一步是由GSTZ 1 -1催化脱氯生成乙醛酸。GSTZ 1 -1也称为马来酰乙酰乙酸异构酶，在酪氨酸的催化中起重要作用，主要在肝脏中表达，是已知催化卤代乙酸（包括DCA）脱卤的唯一酶。虽然众所周知，DCA抑制其自身代谢和马来酰乙酰乙酸及其脱羧产物马来酰丙酮的代谢，几乎可以肯定是因为DCA使GSTZ 1 -1失活，但重复给药后DCA药代动力学的显著个体差异的原因才刚刚开始被理解。大多数成年人清除重复剂量的DCA比大多数儿童慢。具有不同GSTZ 1 -1单倍型的人对DCA重复剂量的反应似乎不同。最近的体外研究表明，氯离子浓度影响GSTZ 1 -1的失活率的DCA单倍型依赖性的方式。除了其众所周知的存在于肝细胞质中，GSTZ 1 -1最近被发现存在于线粒体基质中。这与丙酮酸脱氢酶激酶（DCA的药效学作用部位）的位置相同。DCA代谢物乙醛酸的大部分下游代谢发生在线粒体中，这表明该位点在DCA的总体处置中的重要性。该申请旨在研究GSTZ 1 -1在人类寿命中表达和活性的年龄相关变化，并确定新发现的线粒体酶的特性。提出了三个具体目标。第一个具体的目标将调查年龄相关的变化，肝GSTZ 1 -1的表达和活性的线粒体和胞质溶胶。第二个具体目标将检查线粒体酶的性质，关于线粒体相对于胞质GSTZ 1 -1在体内暴露于DCA后的相对损失，以及线粒体GSTZ 1 -1/MAAI将GSTZ 1 -1的生理重要底物马来酰丙酮转化为富马酰丙酮的能力。第三个具体目标将使用体外研究来调查线粒体GSTZ 1 -1对DCA失活的敏感性，以及氯离子和单倍型作为细胞溶质、线粒体和表达的GSTZ 1 -1被DCA失活的速率和机制的决定因素的作用。