title: Impaired very long-chain acyl-CoA β-oxidation in human X-linked adrenoleukodystrophy fibroblasts is a direct consequence of ABCD1 transporter dysfunction.
abstract: X-linked adrenoleukodystrophy (X-ALD), an inherited peroxisomal disorder, is caused by mutations in the ABCD1 gene encoding the peroxisomal ATP-binding cassette (ABC) transporter ABCD1 (adrenoleukodystrophy protein, ALDP). Biochemically, X-ALD is characterized by an accumulation of very long-chain fatty acids and partially impaired peroxisomal β-oxidation. In this study, we used primary human fibroblasts from X-ALD and Zellweger syndrome patients to investigate the peroxisomal β-oxidation defect. Our results show that the degradation of C26:0-CoA esters is as severely impaired as degradation of unesterified very long-chain fatty acids in X-ALD and is abolished in Zellweger syndrome. Interestingly, the β-oxidation rates for both C26:0-CoA and C22:0-CoA were similarly affected, although C22:0 does not accumulate in patient fibroblasts. Furthermore, we show that the β-oxidation defect in X-ALD is directly caused by ABCD1 dysfunction as blocking ABCD1 function with a specific antibody reduced β-oxidation to levels observed in X-ALD fibroblasts. By quantification of mRNA and protein levels of the peroxisomal ABC transporters and by blocking with specific antibodies, we found that residual β-oxidation activity toward C26:0-CoA in X-ALD fibroblasts is mediated by ABCD3, although the efficacy of ABCD3 appeared to be much lower than that of ABCD1. Finally, using isolated peroxisomes, we show that β-oxidation of C26:0-CoA is independent of additional CoA but requires a cytosolic factor of >10-kDa molecular mass that is resistant to N-ethylmaleimide and heat inactivation. In conclusion, our findings in human cells suggest that, in contrast to yeast cells, very long-chain acyl-CoA esters are transported into peroxisomes by ABCD1 independently of additional synthetase activity.
authors.affiliation: Center for Brain Research, Medical University of Vienna, Spitalgasse 4, 1090 Vienna, Austria.
authors.forename: Christoph
authors.initials: C
authors.lastname: Wiesinger
authors.forename: Markus
authors.initials: M
authors.lastname: Kunze
authors.forename: Günther
authors.initials: G
authors.lastname: Regelsberger
authors.forename: Sonja
authors.initials: S
authors.lastname: Forss-Petter
authors.forename: Johannes
authors.initials: J
authors.lastname: Berger
mesh_terms: D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D000074063:ATP Binding Cassette Transporter, Subfamily D, Member 1; D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism*; D000214:Acyl Coenzyme A / Q000378:metabolism*; D000326:Adrenoleukodystrophy / Q000378:metabolism*; D001692:Biological Transport; D003600:Cytosol / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D008297:Male; D010100:Oxygen / Q000378:metabolism; D020675:Peroxisomes / Q000378:metabolism; D012867:Skin / Q000473:pathology; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: C115572:ABCD1 protein, human; D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D000074063:ATP Binding Cassette Transporter, Subfamily D, Member 1; D018528:ATP-Binding Cassette Transporters; D000214:Acyl Coenzyme A; D005227:Fatty Acids; C071692:TAP2 protein, human; C007547:behenic acid; D010100:Oxygen
keywords: ABC Transporter; ABCD1; ABCD3; Adrenoleukodystrophy Protein; Fatty Acid Transport; Metabolic Diseases; Peroxisomes; VLCFA; X-ALD; β-Oxidation