Inborn Errors of Long Chain Fat Metabolism

长链脂肪代谢先天性错误

基本信息

批准号：
7595857
负责人：
GERARD VOCKLEY
金额：
$ 30.11万
依托单位：
UNIVERSITY OF PITTSBURGH AT PITTSBURGH
依托单位国家：
美国
项目类别：
财政年份：
2008
资助国家：
美国
起止时间：
2008-04-01 至 2012-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7595857
关键词：
Acute Liver Failure Acyl CoA Dehydrogenases Acyl Coenzyme A Affect Alternative Splicing Amino Acid Motifs Amino Acids Bile Acid Biosynthesis Pathway Bile Acids Biogenesis Cardiomyopathies Catabolism Cell Nucleus Cells Chemicals Chenodeoxycholic Acid Clinical Coenzyme A Data Defect Development Disease Enzymes Equilibrium Esters Family Fatty Acids Fatty Liver Gene Family Generations Genetic Genotype Goals Hereditary Disease Human Inborn Errors of Metabolism Inborn Genetic Diseases Inner mitochondrial membrane Knockout Mice Lead Learning Lecithin Length Liver Failure Location Long-Chain-Acyl-CoA Dehydrogenase Metabolic Metabolic Pathway Metabolism Mitochondria Molecular Molecular Conformation Mus Mutation Pathway interactions Patients Pattern Phenotype Physiological Preparation Process Proteins Reye Syndrome Role Structure-Activity Relationship Substrate Specificity Tissues Variant acyl-CoA dehydrogenase base dehydrogenation enzyme deficiency fatty acid oxidation in vivo lipid metabolism member mouse model mutant novel oxidation surfactant

项目摘要

DESCRIPTION (provided by applicant): The acyl-CoA dehydrogenases (ACDs) are a family of multimeric flavoenzymes that catalyze the 1,2- dehydrogenation of acyl-CoA esters in fatty acid 2-oxidation and amino acid catabolism. Inborn errors of metabolism have been identified in seven of the ACDs. The long range objective of this project has been to investigate important structure/function relationships in the ACD gene family. We have described and characterized several new members of the ACD gene family. Among these are 3 enzymes with significant activities with long chain substrates: long and very long chain acyl-CoA dehydrogenases (LCAD and VLCAD, respectively), and ACD9 and. Our prior and preliminary studies show that these enzymes have distinct substrate utilization profiles, tissue and developmental expression patterns, exist in multiple active forms in the cell, and are present in multiple subcellular locations. The goal of this revised application is to characterize the physiologic roles of LCAD, VLCAD, and ACD9 and explore the ramifications of genetic deficiencies of these enzymes in humans and mouse models. Specific Aim 1 is to characterize variant forms of very long chain acyl-CoA dehydrogenase (VLCAD) and the molecular basis of clinical variability in this disorder. Specific aim 1a is to identify the amino acid motif(s) important in determining the unique localization of VLCAD to the inner mitochondrial membrane. Specific aim 1b is to characterize alternative forms of VLCAD identified in vivo. We have identified 3 variant forms of this enzyme in vivo that are generated through alternative splicing. I hypothesize that each has a different substrate specificity that provides functional optimization for progressively shorter substrate species. Specific aim 1c is to characterize the effect of patient mutations in VLCAD on enzyme function. Specific Aim 2 is to more completely characterize ACD9 and its deficiency in humans. Specific Aim 2a is identification of additional patients with ACD9 deficiency and definition of its clinical spectrum. Specific Aim 2b is characterization of the subcellular distribution of ACD9 and the function and molecular configuration of ACD9 protein outside of mitochondria. I hypothesize that this alternative form of ACD9 has non-enzymatic "moonlighting" functions in the cell. Specific Aim 3 is to elucidate the physiologic function of LCAD. Despite its early recognition, its in vivo metabolic role remains a mystery. Our preliminary data implicates it in bile acid and surfactant metabolism. Specific Aim 3a is to characterize the role of LCAD in bile acid synthesis. I hypothesize that it characterizes a key intermediate step in chenodeoxycholic acid synthesis in a mitochondrial based acidic pathway that is involved in the control of cellular metabolic rate. Specific Aim 3b is to explore the role of LCAD in surfactant metabolism using an LCAD null mouse. These studies necessitate a fundamental revision in our view of mitochondrial 2-oxidation from a metabolic pathway that is only responsible for energy generation to one that is active as well in a variety of previously unrec- ognized functions in other important biologic processes.The acyl-CoA dehydrogenases are important enzymes in maintaining normal chemical balance in the body. We have identified a new genetic disorder of one of these enzymes that leads to liver failure. Studying this disorder is important to learn more about its clinical presentation and treatment.

描述（由申请人提供）：酰基辅酶 A 脱氢酶 (ACD) 是一个多聚黄素酶家族，可催化脂肪酸 2-氧化和氨基酸分解代谢中酰基辅酶 A 酯的 1,2-脱氢。在七种 ACD 中已发现先天性代谢缺陷。该项目的长期目标是研究 ACD 基因家族中重要的结构/功能关系。我们已经描述并表征了 ACD 基因家族的几个新成员。其中有 3 种酶对长链底物具有显着活性：长链和极长链酰基辅酶 A 脱氢酶（分别为 LCAD 和 VLCAD）以及 ACD9 和。我们之前和初步的研究表明，这些酶具有不同的底物利用概况、组织和发育表达模式，在细胞中以多种活性形式存在，并且存在于多个亚细胞位置。此修订应用程序的目标是表征 LCAD、VLCAD 和 ACD9 的生理作用，并探索这些酶的遗传缺陷在人类和小鼠模型中的影响。具体目标 1 是表征极长链酰基辅酶 A 脱氢酶 (VLCAD) 的变异形式以及该疾病临床变异的分子基础。具体目标 1a 是鉴定对于确定 VLCAD 线粒体内膜的独特定位很重要的氨基酸基序。具体目标 1b 是表征体内鉴定的 VLCAD 替代形式。我们已经在体内鉴定了这种酶的 3 种变体形式，它们是通过选择性剪接产生的。我假设每种都有不同的底物特异性，为逐渐较短的底物种类提供功能优化。具体目标 1c 是表征 VLCAD 中患者突变对酶功能的影响。具体目标 2 是更完整地表征 ACD9 及其在人类中的缺陷。具体目标 2a 是识别其他 ACD9 缺陷患者并定义其临床谱。具体目标 2b 是表征 ACD9 的亚细胞分布以及 ACD9 蛋白在线粒体外的功能和分子构型。我推测 ACD9 的这种替代形式在细胞中具有非酶促的“兼职”功能。具体目标 3 是阐明 LCAD 的生理功能。尽管它很早就被认识，但它在体内的代谢作用仍然是个谜。我们的初步数据表明它与胆汁酸和表面活性剂代谢有关。具体目标 3a 是表征 LCAD 在胆汁酸合成中的作用。我假设它表征了基于线粒体的酸性途径中鹅去氧胆酸合成的关键中间步骤，该途径涉及细胞代谢率的控制。具体目标 3b 是使用 LCAD 缺失小鼠探索 LCAD 在表面活性剂代谢中的作用。这些研究需要对我们对线粒体 2-氧化的看法进行根本性的修正，从一种只负责能量产生的代谢途径转变为一种在其他重要生物过程中还参与各种先前未识别的功能的途径。 CoA脱氢酶是维持体内正常化学平衡的重要酶。我们已经发现了其中一种酶的一种新的遗传性疾病，它会导致肝衰竭。研究这种疾病对于更多地了解其临床表现和治疗非常重要。