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Cell Rep. 2019 Apr 30;27(5):1376-1386.e6. doi: 10.1016/j.celrep.2019.04.005.

Functional Assessment of Lipoyltransferase-1 Deficiency in Cells, Mice, and Humans.

Author information

1
Children's Medical Center Research Institute, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA. Electronic address: min.ni@utsouthwestern.edu.
2
Children's Medical Center Research Institute, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
3
Children's Medical Center Research Institute, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Quantitative Biomedical Research Center, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
4
Department of Molecular and Cellular Endocrinology, City of Hope, Duarte, CA 91010, USA.
5
Howard Hughes Medical Institute, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
6
Department of Molecular Genetics, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
7
Department of Pathology, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
8
Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Howard Hughes Medical Institute, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
9
Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Eugene McDermott Center for Human Growth and Development, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
10
Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Eugene McDermott Center for Human Growth and Development, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Neurology and Neurotherapeutics, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Physiology, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
11
Children's Medical Center Research Institute, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Eugene McDermott Center for Human Growth and Development, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Howard Hughes Medical Institute, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA. Electronic address: ralph.deberardinis@utsouthwestern.edu.

Abstract

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.

KEYWORDS:

2-ketoacid dehydrogenase; epilepsy,developmental delay; fatty acid oxidation; genomics; inborn errors of metabolism; lactic acidosis; lipogenesis; lipoylation; metabolomics

PMID:
31042466
DOI:
10.1016/j.celrep.2019.04.005
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