Abstract
Using a combination of N-ethyl-N-nitrosourea-mediated mutagenesis and metabolomics-guided screening, we identified mice with elevated blood levels of short-chain C4-acylcarnitine and increased urine isobutyryl-glycine. Genome-wide homozygosity screening, followed by fine mapping, located the disease gene to 15-25 Mb of mouse chromosome 9 where a candidate gene, Acad8, encoding mitochondrial isobutyryl-CoA dehydrogenase was located. Genomic DNA sequencing revealed a single-nucleotide mutation at -17 of the first intron of Acad8 in affected mice. cDNA sequencing revealed an intronic 28-bp insertion at the site of the mutation, which caused a frame shift with a premature stop codon. In vitro splicing assay confirmed that the mutation was sufficient to activate an upstream, aberrant 3' splice site. There was a reduction in the expression of Acad8 at both the mRNA and protein levels. The mutant mice grew normally but demonstrated cold intolerance at young age with a progressive hepatic steatosis. Homozygous mutant mice hepatocytes had abnormal mitochondria with crystalline inclusions, suggestive of mitochondriopathy. This mouse model of isobutyryl-CoA dehydrogenase deficiency could provide us a better understanding of the possible role of IBD deficiency in mitochondriopathy and fatty liver.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Acyl-CoA Dehydrogenase / deficiency
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Acyl-CoA Dehydrogenase / genetics
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Alternative Splicing*
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Amino Acid Metabolism, Inborn Errors / enzymology*
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Amino Acid Metabolism, Inborn Errors / genetics
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Amino Acid Metabolism, Inborn Errors / pathology
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Amino Acid Metabolism, Inborn Errors / physiopathology
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Animals
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Base Sequence
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Cold Temperature
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DNA Mutational Analysis
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Disease Models, Animal
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Disease Progression
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Ethylnitrosourea / pharmacology
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Fatty Liver / enzymology*
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Fatty Liver / genetics
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Fatty Liver / pathology
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Gene Expression Regulation, Enzymologic
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Genetic Predisposition to Disease
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Liver X Receptors
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Male
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Metabolomics / methods
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Mice
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Mice, Inbred C57BL
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Mice, Mutant Strains
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Microscopy, Electron, Transmission
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Mitochondria, Liver / enzymology*
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Mitochondria, Liver / ultrastructure
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Mitochondrial Swelling
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Molecular Sequence Data
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Mutagens / pharmacology
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Mutation
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Orphan Nuclear Receptors / metabolism
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Oxidoreductases Acting on CH-CH Group Donors / deficiency
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Oxidoreductases Acting on CH-CH Group Donors / genetics
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Oxidoreductases Acting on CH-CH Group Donors / metabolism*
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PPAR alpha / metabolism
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PPAR gamma / metabolism
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Phenotype
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RNA, Messenger / metabolism
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Thermogenesis
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Thermosensing
Substances
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Liver X Receptors
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Mutagens
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Orphan Nuclear Receptors
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PPAR alpha
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PPAR gamma
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RNA, Messenger
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Oxidoreductases Acting on CH-CH Group Donors
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Acyl-CoA Dehydrogenase
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2-methylacyl-CoA dehydrogenase
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Ethylnitrosourea
Supplementary concepts
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Isobutyryl-CoA dehydrogenase deficiency