title: CYP4F3B expression is associated with differentiation of HepaRG human hepatocytes and unaffected by fatty acid overload.
abstract: Fatty acid microsomal ω-oxidation involves cytochrome P450 enzymes. Some of them belonging to the CYP4F3 family are mainly expressed in the liver, making this organ a major player in energy homeostasis and lipid metabolism. To study this important regulation pathway, we used HepaRG cells, which gradually undergo a complete differentiation process. Even at the early stage of the differentiation process, CYP4F3B generated by alternative splicing of the CYP4F3 gene represented the prevalent isoform in HepaRG cells as in the liver. Its increasing expression associated with hepatocyte differentiation status suggested a hepatic-specific control of this isoform. As in liver microsomes, the catalytic hydroxylation of the CYP4F3B substrate [1-¹⁴C]Z9(10)-epoxystearic acid led to major production of 18-hydroxy-9(10)-epoxystearic acid. When treated with saturated, monounsaturated, or polyunsaturated fatty acids, CYP4F3B and CYP4A11 expression remained unchanged whereas CYP4F2 and CYP4F12 expression was transiently up-regulated. A 24-h exposure of differentiated HepaRG cells to various polyunsaturated fatty acids and derivatives induced microvesicular steatosis; down-regulation of lipid metabolism gene regulators such as sterol regulatory element-binding protein-1c, fatty acid synthase, peroxisome proliferator-activated receptor γ (PPARγ), PPARα, and decreased expression of glucose-dependent metabolism genes, which could limit de novo lipogenesis. Docosahexaenoic acid seemed to be the most effective compound. These results suggest that a PPARα-independent pathway could participate to limit lipogenesis and emphasize the role of hepatocytes in the fatty acid ω-hydroxylation pathway. They also give insights on the use of HepaRG hepatocytes to open new avenues of investigations on factors mediating the lipid metabolic pathway and finding new hypolipidemic molecules.
authors.affiliation: Centre National de la Recherche Scientifique, UMR 7139, Station Biologique, Roscoff, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Madec
authors.forename: Virginie
authors.initials: V
authors.lastname: Cerec
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Plée-Gautier
authors.forename: Joseph
authors.initials: J
authors.lastname: Antoun
authors.forename: Denise
authors.initials: D
authors.lastname: Glaise
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Salaun
authors.forename: Christiane
authors.initials: C
authors.lastname: Guguen-Guillouzo
authors.forename: Anne
authors.initials: A
authors.lastname: Corlu
mesh_terms: D017398:Alternative Splicing; D002454:Cell Differentiation / Q000502:physiology*; D002460:Cell Line; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D000072470:Cytochrome P450 Family 4; D004281:Docosahexaenoic Acids / Q000378:metabolism; D064429:Fatty Acid Synthases / Q000235:genetics / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D022781:Hepatocytes / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism*; D006801:Humans; D006900:Hydroxylation; D050356:Lipid Metabolism; D050155:Lipogenesis; D008099:Liver / Q000378:metabolism; D008862:Microsomes, Liver / Q000378:metabolism; D047493:PPAR alpha / Q000235:genetics / Q000378:metabolism; D047495:PPAR gamma / Q000235:genetics / Q000378:metabolism; D020033:Protein Isoforms; D051780:Sterol Regulatory Element Binding Protein 1 / Q000378:metabolism
chemical_list: D005227:Fatty Acids; D047493:PPAR alpha; D047495:PPAR gamma; D020033:Protein Isoforms; D051780:Sterol Regulatory Element Binding Protein 1; D004281:Docosahexaenoic Acids; D003577:Cytochrome P-450 Enzyme System; D000072470:Cytochrome P450 Family 4; C465349:CYP4F3 protein, human; D064429:Fatty Acid Synthases