Functional Assessment of Lipoyltransferase-1 Deficiency in Cells, Mice, and Humans
Inborn errors of metabolism (IEMs) link metabolic defects to human phenotypes. Modern genomics has accelerated IEM discovery, but assessing the impact of genomic variants is still challenging. Here, we integrate genomics and metabolomics to identify a cause of lactic acidosis and epilepsy. The proba...
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Published in | Cell reports (Cambridge) Vol. 27; no. 5; pp. 1376 - 1386.e6 |
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Main Authors | , , , , , , , , , , , , , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
Elsevier Inc
30.04.2019
Elsevier |
Subjects | |
Online Access | Get full text |
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Summary: | Inborn errors of metabolism (IEMs) link metabolic defects to human phenotypes. Modern genomics has accelerated IEM discovery, but assessing the impact of genomic variants is still challenging. Here, we integrate genomics and metabolomics to identify a cause of lactic acidosis and epilepsy. The proband is a compound heterozygote for variants in LIPT1, which encodes the lipoyltransferase required for 2-ketoacid dehydrogenase (2KDH) function. Metabolomics reveals abnormalities in lipids, amino acids, and 2-hydroxyglutarate consistent with loss of multiple 2KDHs. Homozygous knockin of a LIPT1 mutation reduces 2KDH lipoylation in utero and results in embryonic demise. In patient fibroblasts, defective 2KDH lipoylation and function are corrected by wild-type, but not mutant, LIPT1 alleles. Isotope tracing reveals that LIPT1 supports lipogenesis and balances oxidative and reductive glutamine metabolism. Altogether, the data extend the role of LIPT1 in metabolic regulation and demonstrate how integrating genomics and metabolomics can uncover broader aspects of IEM pathophysiology.
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•Human LIPT1 mutations impair 2-ketoacid dehydrogenase lipoylation and activity•LIPT1 deficiency increases 2-HG and depletes structural lipids in plasma•LIPT1 deficiency impedes lipogenesis but increases fatty acid oxidation•LIPT1 regulates the balance between oxidative and reductive glutamine metabolism
Ni et al. investigate human LIPT1 deficiency, which results in developmental delay, epilepsy, and broad metabolic abnormalities, including lactic acidosis, L- and D-2-hydroxyglutaric aciduria, defective lipogenesis, and an altered balance between oxidative and reductive glutamine metabolism. |
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Bibliography: | ObjectType-Case Study-2 SourceType-Scholarly Journals-1 ObjectType-Feature-4 content type line 23 ObjectType-Report-1 ObjectType-Article-3 AUTHOR CONTRIBUTIONS M.N. and R.J.D. designed the research and wrote the manuscript. M.N., G.K.G., and R.J.D. recruited patients, managed the clinical study, and analyzed the data. M.N., A.N., N.M.M., and G.G. managed biobanking. M.N., A.S., D.L., C.P., A.N., B.F., L.J., B.K., and C.Y. performed the experiments. M.N., A.N., N.M.M., L.G.Z., L.C., G.G., and H.S.V. designed and performed the metabolomics. M.N., J.P., and N.V.G. analyzed protein structure. M.N., G. V., and J.G.M. performed the lipidomics. D.R. measured 2-hydroxyglutarate. |
ISSN: | 2211-1247 2211-1247 |
DOI: | 10.1016/j.celrep.2019.04.005 |