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Adipocyte differentiation of 3T3-L1 preadipocytes is dependent on lipoxygenase activity during the initial stages of the differentiation process

2003; Portland Press; Volume: 375; Issue: 3 Linguagem: Inglês

10.1042/bj20030503

1470-8728

Lise Madsen, Rasmus K. Petersen, Morten Beck Sørensen, Claus Jørgensen, Philip Hallenborg, Lone Pridal, Jan Fleckner, Ez‐Zoubir Amri, Peter Krieg, Gerhard Fürstenberger, Rolf K. Berge, Karsten Kristiansen,

Adipose Tissue and Metabolism

Adipocytes play a central role in whole-body energy homoeostasis. Complex regulatory transcriptional networks control adipogensis, with ligand-dependent activation of PPARgamma (peroxisome proliferator-activated receptor gamma) being a decisive factor. Yet the identity of endogenous ligands promoting adipocyte differentiation has not been established. Here we present a critical evaluation of the role of LOXs (lipoxygenases) during adipocyte differentiation of 3T3-L1 cells. We show that adipocyte differentiation of 3T3-L1 preadipocytes is inhibited by the general LOX inhibitor NDGA (nordihydroguaiaretic acid) and the 12/15-LOX selective inhibitor baicalein. Baicalein-mediated inhibition of adipocyte differentiation was rescued by administration of rosiglitazone. Treatment with baicalein during the first 4 days of the differentiation process prevented adipocyte differentiation; supplementation with rosiglitazone during the same period was sufficient to rescue adipogenesis. Accordingly, we demonstrate that adipogenic conversion of 3T3-L1 cells requires PPARgamma ligands only during the first 4 days of the differentiation process. We show that the baicalein-sensitive synthesis of endogenous PPARgamma ligand(s) increases rapidly upon induction of differentiation and reaches a maximum on days 3-4 of the adipocyte differentiation programme. The conventional platelet- and leucocyte-type 12(S)-LOXs and the novel eLOX-3 (epidermis-type LOX-3) are expressed in white and brown adipose tissue, whereas only eLOX-3 is clearly expressed in 3T3-L1 cells. We suggest that endogenous PPARgamma ligand(s) promoting adipocyte differentiation are generated via a baicalein-sensitive pathway involving the novel eLOX-3.