title: Alternative splicing in Acad8 resulting a mitochondrial defect and progressive hepatic steatosis in mice.
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.
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Nagham George Abd Al-Ahad
authors.initials: NG
authors.lastname: Sabbagha
authors.forename: Hsiao-Jung
authors.initials: HJ
authors.lastname: Kao
authors.forename: Chih-Fu
authors.initials: CF
authors.lastname: Yang
authors.forename: Cheng-Chih
authors.initials: CC
authors.lastname: Huang
authors.forename: Wei-De
authors.initials: WD
authors.lastname: Lin
authors.forename: Fuu-Jen
authors.initials: FJ
authors.lastname: Tsai
authors.forename: Tzu-Ho
authors.initials: TH
authors.lastname: Chen
authors.forename: Woan-Yuh
authors.initials: WY
authors.lastname: Tarn
authors.forename: Jer-Yuarn
authors.initials: JY
authors.lastname: Wu
authors.forename: Yuan-Tsong
authors.initials: YT
authors.lastname: Chen
mesh_terms: D042964:Acyl-CoA Dehydrogenase / Q000172:deficiency / Q000235:genetics; D017398:Alternative Splicing; D000592:Amino Acid Metabolism, Inborn Errors / Q000201:enzymology* / Q000235:genetics / Q000473:pathology / Q000503:physiopathology; D000818:Animals; D001483:Base Sequence; D003080:Cold Temperature; D004252:DNA Mutational Analysis; D004195:Disease Models, Animal; D018450:Disease Progression; D005038:Ethylnitrosourea / Q000494:pharmacology; D005234:Fatty Liver / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D015971:Gene Expression Regulation, Enzymologic; D020022:Genetic Predisposition to Disease; D000071518:Liver X Receptors; D008297:Male; D055432:Metabolomics / Q000379:methods; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D046529:Microscopy, Electron, Transmission; D008930:Mitochondria, Liver / Q000201:enzymology* / Q000648:ultrastructure; D008933:Mitochondrial Swelling; D008969:Molecular Sequence Data; D009153:Mutagens / Q000494:pharmacology; D009154:Mutation; D057093:Orphan Nuclear Receptors / Q000378:metabolism; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D047493:PPAR alpha / Q000378:metabolism; D047495:PPAR gamma / Q000378:metabolism; D010641:Phenotype; D012333:RNA, Messenger / Q000378:metabolism; D022722:Thermogenesis; D013697:Thermosensing
chemical_list: D000071518:Liver X Receptors; D009153:Mutagens; D057093:Orphan Nuclear Receptors; D047493:PPAR alpha; D047495:PPAR gamma; D012333:RNA, Messenger; D044925:Oxidoreductases Acting on CH-CH Group Donors; D042964:Acyl-CoA Dehydrogenase; C038808:2-methylacyl-CoA dehydrogenase; D005038:Ethylnitrosourea