title: Dexamethasone reverses TGF-beta-mediated inhibition of primary rat preadipocyte differentiation.
abstract: Dexamethasone and transforming growth factor-beta (TGF-beta) show contrary effects on differentiation of adipocytes. Dexamethasone stimulates adipocyte differentiation whereas TGF-beta inhibits it. In the present study, we investigated whether dexamethasone could reverse the TGF-beta-mediated inhibition of preadipocyte differentiation. Primary rat preadipocytes, obtained from Sprague-Dawley rats, were pretreated with dexamethasone in the presence or absence of TGF-beta, prior to the induction of differentiation. Co-treatment of dexamethasone and TGF-beta before inducing differentiation reversed the TGF-beta-mediated inhibition of preadipocyte differentiation. In order to elucidate the mechanism by which dexamethasone reversed the effect of TGF-beta on the inhibition of preadipocyte differentiation, the expression of CCAAT/enhancer binding protein-alpha (C/EBPalpha) and peroxisome proliferator-activated receptor gamma (PPARgamma) was examined. Dexamethasone increased C/EBPalpha and PPARgamma expression in the absence of TGF-beta and also recovered the TGF-beta-mediated suppression of C/EBPalpha expression in preadipocytes. Its effect was sustained in differentiated adipocytes as well. However, those effects were not observed in 3T3-L1 preadipocytes or differentiated adipocytes. These results indicate that dexamethasone reverses the TGF-beta-mediated suppression of adipocyte differentiation by regulating the expression of C/EBPalpha and PPARgamma, which is dependent on the cellular context.
authors.affiliation: Laboratory of Immunology, Korea Research Institute of Bioscience and Biotechnology, 305-333, Daejon, South Korea.
authors.forename: Sun Mi
authors.initials: SM
authors.lastname: Shin
authors.forename: Kun yong
authors.initials: Ky
authors.lastname: Kim
authors.forename: Jae Kwang
authors.initials: JK
authors.lastname: Kim
authors.forename: Suk Ran
authors.initials: SR
authors.lastname: Yoon
authors.forename: Inpyo
authors.initials: I
authors.lastname: Choi
authors.forename: Young
authors.initials: Y
authors.lastname: Yang
mesh_terms: D017667:Adipocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000096:biosynthesis; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002478:Cells, Cultured; D003907:Dexamethasone / Q000494:pharmacology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D016212:Transforming Growth Factor beta / Q000037:antagonists & inhibitors*
chemical_list: D022763:CCAAT-Enhancer-Binding Protein-alpha; D016212:Transforming Growth Factor beta; D003907:Dexamethasone