Alternative splicing in Acad8 resulting a mitochondrial defect and progressive hepatic steatosis in mice

Pediatr Res. 2011 Jul;70(1):31-6. doi: 10.1203/PDR.0b013e31821b89ee.

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

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acyl-CoA Dehydrogenase / deficiency
  • Acyl-CoA Dehydrogenase / genetics
  • Alternative Splicing*
  • Amino Acid Metabolism, Inborn Errors / enzymology*
  • Amino Acid Metabolism, Inborn Errors / genetics
  • Amino Acid Metabolism, Inborn Errors / pathology
  • Amino Acid Metabolism, Inborn Errors / physiopathology
  • Animals
  • Base Sequence
  • Cold Temperature
  • DNA Mutational Analysis
  • Disease Models, Animal
  • Disease Progression
  • Ethylnitrosourea / pharmacology
  • Fatty Liver / enzymology*
  • Fatty Liver / genetics
  • Fatty Liver / pathology
  • Gene Expression Regulation, Enzymologic
  • Genetic Predisposition to Disease
  • Liver X Receptors
  • Male
  • Metabolomics / methods
  • Mice
  • Mice, Inbred C57BL
  • Mice, Mutant Strains
  • Microscopy, Electron, Transmission
  • Mitochondria, Liver / enzymology*
  • Mitochondria, Liver / ultrastructure
  • Mitochondrial Swelling
  • Molecular Sequence Data
  • Mutagens / pharmacology
  • Mutation
  • Orphan Nuclear Receptors / metabolism
  • Oxidoreductases Acting on CH-CH Group Donors / deficiency
  • Oxidoreductases Acting on CH-CH Group Donors / genetics
  • Oxidoreductases Acting on CH-CH Group Donors / metabolism*
  • PPAR alpha / metabolism
  • PPAR gamma / metabolism
  • Phenotype
  • RNA, Messenger / metabolism
  • Thermogenesis
  • Thermosensing

Substances

  • Liver X Receptors
  • Mutagens
  • Orphan Nuclear Receptors
  • PPAR alpha
  • PPAR gamma
  • RNA, Messenger
  • Oxidoreductases Acting on CH-CH Group Donors
  • Acyl-CoA Dehydrogenase
  • 2-methylacyl-CoA dehydrogenase
  • Ethylnitrosourea

Supplementary concepts

  • Isobutyryl-CoA dehydrogenase deficiency