Peroxisomal fatty acid beta-oxidation in HepG2 cells.
HepG2 cells, originally derived from a human hepatoblastoma, contain peroxisomes which could be separated from mitochondria and other subcellular organelles by density gradient centrifugation. To determine whether this cell line was a suitable model for human peroxisomal fatty acid beta-oxidation, we investigated the ability of these cells to catabolize very-long-chain fatty acids (VLCFA). HepG2 cell homogenates or digitonin-disrupted cells oxidized both long chain fatty acids and VLCFA, although at somewhat lower rates than human liver homogenates. beta-Oxidation of VLCFA was observed in both peroxisomes and mitochondria of HepG2 cells. Peroxisomal beta-oxidation was independent of carnitine, insensitive to antimycin A and rotenone, and not blocked by an inhibitor of carnitine palmitoyl transferase I. HepG2 peroxisomes contained immunoreactive acyl-CoA oxidase, the first enzyme unique to the peroxisomal beta-oxidation pathway. In addition, HepG2 peroxisomes contained VLCFA-CoA synthetase activity. These results suggest that HepG2 may be a useful model system for the study of human peroxisomal metabolic processes, including beta-oxidation of fatty acids.
Watkins
P A
PA
Kennedy Institute, Baltimore, Maryland 21205.
Ferrell
E V
EV
Pedersen
J I
JI
Hoefler
G
G
D042962:Acyl-CoA Oxidase; D000968:Antimycin A / Q000494:pharmacology; D006528:Carcinoma, Hepatocellular / Q000378:metabolism; D002331:Carnitine / Q000378:metabolism; D002460:Cell Line; D003066:Coenzyme A Ligases / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism*; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism; D008830:Microbodies / Q000378:metabolism*; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism
D005227:Fatty Acids; D000968:Antimycin A; D010088:Oxidoreductases; D042962:Acyl-CoA Oxidase; D003066:Coenzyme A Ligases; D002331:Carnitine