title: Nuclear factor-κB is a common upstream signal for growth differentiation factor-5 expression in brown adipocytes exposed to pro-inflammatory cytokines and palmitate.
abstract: We have previously demonstrated that genetic and acquired obesity similarly led to drastic upregulation in brown adipose tissue (BAT), rather than white adipose tissue, of expression of both mRNA and corresponding protein for the bone morphogenic protein/growth differentiation factor (GDF) member GDF5 capable of promoting brown adipogenesis. In this study, we evaluated expression profiles of GDF5 in cultured murine brown pre-adipocytes exposed to pro-inflammatory cytokines and free fatty acids (FFAs), which are all shown to play a role in the pathogenesis of obesity. Both interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) were effective in up-regulating GDF5 expression in a concentration-dependent manner, while similar upregulation was seen in cells exposed to the saturated FFA palmitate, but not to the unsaturated FFA oleate. In silico analysis revealed existence of the putative nuclear factor-κB (NF-κB) binding site in the 5'-flanking region of mouse GDF5, whereas introduction of NF-κB subunits drastically facilitated both promoter activity and expression of GDF5 in brown pre-adipocytes. Chromatin immunoprecipitation analysis confirmed significant facilitation of the recruitment of NF-κB to the GDF5 promoter in lysed extracts of BAT from leptin-deficient ob/ob obese mice. Upregulation o GDF5 expression was invariably inhibited by an NF-κB inhibitor in cultured brown pre-adipocytes exposed to IL-1β, TNF-α and palmitate. These results suggest that obesity leads to upregulation of GDF5 expression responsible for the promotion of brown adipogenesis through a mechanism relevant to activation of the NF-κB pathway in response to particular pro-inflammatory cytokines and/or saturated FFAs in BAT.
authors.affiliation: Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School, Kanazawa, Ishikawa 920-1192, Japan.
authors.forename: Eiichi
authors.initials: E
authors.lastname: Hinoi
authors.affiliation: Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School, Kanazawa, Ishikawa 920-1192, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Iezaki
authors.affiliation: Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School, Kanazawa, Ishikawa 920-1192, Japan.
authors.forename: Kakeru
authors.initials: K
authors.lastname: Ozaki
authors.affiliation: Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School, Kanazawa, Ishikawa 920-1192, Japan. Electronic address: yyoneda@p.kanazawa-u.ac.jp.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Yoneda
mesh_terms: D052437:Adipocytes, Brown / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D016207:Cytokines; D055428:Growth Differentiation Factor 5 / Q000378:metabolism*; D007249:Inflammation / Q000139:chemically induced / Q000150:complications / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D016328:NF-kappa B / Q000378:metabolism*; D009765:Obesity / Q000150:complications / Q000378:metabolism*; D019308:Palmitic Acid
chemical_list: D016207:Cytokines; C525894:Gdf5 protein, mouse; D055428:Growth Differentiation Factor 5; D016328:NF-kappa B; D019308:Palmitic Acid
keywords: Brown adipocytes; GDF5; NF-κB; Obesity; Palmitate; Pro-inflammatory cytokines