title: Reversal of mouse Acyl-CoA oxidase 1 (ACOX1) null phenotype by human ACOX1b isoform [corrected].
abstract: Disruption of the peroxisomal acyl-CoA oxidase 1 (Acox1) gene in the mouse results in the development of severe microvesicular hepatic steatosis and sustained activation of peroxisome proliferator-activated receptor-alpha (PPARalpha). These mice manifest spontaneous massive peroxisome proliferation in regenerating hepatocytes and eventually develop hepatocellular carcinomas. Human ACOX1, the first and rate-limiting enzyme of the peroxisomal beta-oxidation pathway, has two isoforms including ACOX1a and ACOX1b, transcribed from a single gene. As ACOX1a shows reduced activity toward palmitoyl-CoA as compared with ACOX1b, we used adenovirally driven ACOX1a and ACOX1b to investigate their efficacy in the reversal of hepatic phenotype in Acox1(-/-) mice. In this study, we show that human ACOX1b is markedly effective in reversing the ACOX1 null phenotype in the mouse. In addition, expression of human ACOX1b was found to restore the production of nervonic (24:1) acid and had a negative impact on the recruitment of coactivators to the PPARalpha-response unit, which suggests that nervonic acid might well be an endogenous PPARalpha antagonist, with nervonoyl-CoA probably being the active form of nervonic acid. In contrast, restoration of docosahexaenoic (22:6) acid level, a retinoid-X-receptor (RXRalpha) agonist, was dependent on the concomitant hepatic expression of both ACOX1a and ACOX1b isoforms. This is accompanied by a specific recruitment of RXRalpha and coactivators to the PPARalpha-response unit. The human ACOX1b isoform is more effective than the ACOX1a isoform in reversing the Acox1 null phenotype in the mouse. Substrate utilization differences between the two ACOX1 isoforms may explain the reason why ACOX1b is more effective in metabolizing PPARalpha ligands.
authors.affiliation: INSERM, UMR 866, Dijon, France.
authors.forename: Aurore
authors.initials: A
authors.lastname: Vluggens
authors.forename: Pierre
authors.initials: P
authors.lastname: Andreoletti
authors.forename: Navin
authors.initials: N
authors.lastname: Viswakarma
authors.forename: Yuzhi
authors.initials: Y
authors.lastname: Jia
authors.forename: Kojiro
authors.initials: K
authors.lastname: Matsumoto
authors.forename: Wim
authors.initials: W
authors.lastname: Kulik
authors.forename: Mushfiquddin
authors.initials: M
authors.lastname: Khan
authors.forename: Jiansheng
authors.initials: J
authors.lastname: Huang
authors.forename: Dongsheng
authors.initials: D
authors.lastname: Guo
authors.forename: Sangtao
authors.initials: S
authors.lastname: Yu
authors.forename: Joy
authors.initials: J
authors.lastname: Sarkar
authors.forename: Inderjit
authors.initials: I
authors.lastname: Singh
authors.forename: M Sambasiva
authors.initials: MS
authors.lastname: Rao
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Wanders
authors.forename: Janardan K
authors.initials: JK
authors.lastname: Reddy
authors.forename: Mustapha
authors.initials: M
authors.lastname: Cherkaoui-Malki
mesh_terms: D042962:Acyl-CoA Oxidase; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D049109:Cell Proliferation; D004281:Docosahexaenoic Acids / Q000378:metabolism; D005229:Fatty Acids, Monounsaturated / Q000378:metabolism; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D015151:Immunoblotting; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008099:Liver / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D047493:PPAR alpha / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
chemical_list: D005229:Fatty Acids, Monounsaturated; D007527:Isoenzymes; D047493:PPAR alpha; D004281:Docosahexaenoic Acids; C013147:nervonic acid; D010088:Oxidoreductases; C107176:peroxisomal acyl-CoA oxidase; D042962:Acyl-CoA Oxidase