Genomes and Genes
Inborn Errors of Long Chain Fat Metabolism
Principal Investigator: Jerry Vockley
Affiliation: Children's Hospital of Pittsburgh
Abstract: 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.
Funding Period: ------------------20 - -----------------201
more information: NIH RePORT
- Newborn screening: After the thrill is goneJerry Vockley
Department of Pediatrics, School of Medicine, University of Pittsburgh, and Children s Hospital of Pittsburgh, Pittsburgh, PA, USA
Mol Genet Metab 92:6-12. 2007..The Society for Inherited Disorders has been at the forefront of advances in newborn screening for manyyears and faces new challenges in meeting new needs...
- Molecular and cellular pathology of very-long-chain acyl-CoA dehydrogenase deficiencyManuel Schiff
Department of Pediatrics, University of Pittsburgh School of Medicine, University of Pittsburgh, Children s Hospital of Pittsburgh of UPMC, 4401 Penn Avenue, Pittsburgh, PA 15224, USA
Mol Genet Metab 109:21-7. 2013..NBS often unequivocally identifies affected individuals, but a growing number of variant patterns can represent mild disease or heterozygous carriers...
- Metabolomic profiling of amino acids and β-cell function relative to insulin sensitivity in youthSara F Michaliszyn
Children s Hospital of Pittsburgh, 4401 Penn Avenue, Pittsburgh, Pennsylvania 15224, USA
J Clin Endocrinol Metab 97:E2119-24. 2012..In longitudinal studies of adults, elevated amino acid (AA) concentrations predicted future type 2 diabetes mellitus (T2DM)...
- Therapies in inborn errors of oxidative metabolismManuel Schiff
Institut National de la Santé et de la Recherche Médicale Unité 676, Hopital Robert Debre, F 75019 Paris, France
Trends Endocrinol Metab 23:488-95. 2012..In this review present and prospective therapeutic approaches will be discussed on the basis of targets and mechanism of action, but with a broad outlook on their potential applications...
- Novel ETF dehydrogenase mutations in a patient with mild glutaric aciduria type II and complex II-III deficiency in liver and muscleLynne A Wolfe
Division of Medical Genetics, Department of Pediatrics, Children s Hospital of UPMC, Pittsburgh, PA, USA
J Inherit Metab Dis 33:S481-7. 2010....
- Neuropsychological outcomes in fatty acid oxidation disorders: 85 cases detected by newborn screeningSusan E Waisbren
Department of Psychology, Children s Hospital Boston and Harvard Medical School, Boston, Massachusetts 02115, USA
Dev Disabil Res Rev 17:260-8. 2013....
- Recombinant adeno-associated virus-mediated gene delivery of long chain acyl coenzyme A dehydrogenase (LCAD) into LCAD-deficient miceStuart G Beattie
University of Massachusetts Medical School, Worcester, MA 01655, USA
J Gene Med 10:1113-23. 2008..Recombinant adeno-associated viral (rAAV) vectors with pseudotype capsids were investigated for their potential towards correcting the phenotype observed in mice heterozygous (+/-) for LCAD (i.e. liver and muscle steatosis)...
- Metabolism as a complex genetic trait, a systems biology approach: implications for inborn errors of metabolism and clinical diseasesJerry Vockley
Department of Pediatrics, The Children s Hospital of Pittsburgh, University of Pittsburgh School of Medicine, 3705 Fifth Avenue, Pittsburgh, PA 15238, USA
J Inherit Metab Dis 31:619-29. 2008....
- Increased levels of plasma acylcarnitines in obesity and type 2 diabetes and identification of a marker of glucolipotoxicityStephanie J Mihalik
Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
Obesity (Silver Spring) 18:1695-700. 2010..Plasma long-chain AcylCN species are increased in obesity and T2DM, suggesting that more fatty acids can enter mitochondria. In T2DM, many shorter species accumulate, suggesting that they have a generalized complex oxidation defect...
- Efficient and gentle siRNA delivery by magnetofectionR Ensenauer
Children s Research Center, Dr von Hauner Children s Hospital, Ludwig Maximilians Universitat Munchen, Munich, Germany
Biotech Histochem 86:226-31. 2011..These features are especially advantageous for functional end point analyses of gene silencing, e.g., on the metabolite level...
- Metabolomic profiling of fatty acid and amino acid metabolism in youth with obesity and type 2 diabetes: evidence for enhanced mitochondrial oxidationStephanie J Mihalik
Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
Diabetes Care 35:605-11. 2012..We compared acylcarnitine (AcylCN) species, common amino acid and fat oxidation (FOX) byproducts, and plasma amino acids in normal weight (NW; n = 39), obese (OB; n = 64), and type 2 diabetic (n = 17) adolescents...
- Identification and characterization of new long chain acyl-CoA dehydrogenasesMiao He
Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
Mol Genet Metab 102:418-29. 2011....
- Low expression of long-chain acyl-CoA dehydrogenase in human skeletal muscleAmy C Maher
Department of Medical Science, McMaster University, Ontario, Canada
Mol Genet Metab 100:163-7. 2010..The purpose of this study was to investigate the expression levels of LCAD in human skeletal muscle...
- Women have higher protein content of beta-oxidation enzymes in skeletal muscle than menAmy C Maher
Department of Medical Science, McMaster University, Hamilton, Ontario, Canada
PLoS ONE 5:e12025. 2010..In conclusion, women have more protein content of the major enzymes involved in long and medium chain fatty acid oxidation which could account for the observed differences in fat oxidation during exercise...
- Evidence for physical association of mitochondrial fatty acid oxidation and oxidative phosphorylation complexesYudong Wang
Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15224, USA
J Biol Chem 285:29834-41. 2010..These data provide evidence of a multifunctional FAO complex within mitochondria that is physically associated with OXPHOS supercomplexes and promotes metabolic channeling...