title: Luteolin suppresses TCDD-induced wasting syndrome in a cultured adipocyte model.
abstract: 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) causes various toxic effects, including wasting syndrome, through activation of an aryl hydrocarbon receptor (AhR). Our previous report demonstrated that certain flavonoids inhibit the activation of AhR and suppress its DNA binding activity. In this study, we searched for an active compound among 13 flavonoids that suppressed TCDD-induced loss of lipid accumulation using 3T3-L1 adipocytes as a cell culture model for wasting syndrome. Two flavonoids, luteolin and epigallocatechin gallate, suppressed TCDD-induced loss of lipid accumulation in this model. We further investigated luteolin to clarify the underlying molecular mechanism and confirmed that luteolin inhibited nuclear translocation of AhR caused by TCDD. Luteolin also inhibited the TCDD-driven decrease in protein expression of peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα). Although TCDD alone did not change protein expression of C/EBPβ and C/EBPδ, luteolin and TCDD up-regulated C/EBPδ expression in a dose-dependent manner. On the other hand, TCDD significantly decreased DNA binding of C/EBPβ and C/EBPδ, and luteolin completely canceled TCDD-decreased DNA binding of them. We conclude that luteolin suppresses the TCDD-induced loss of lipid accumulation in 3T3-L1 adipocytes by preventing a decrease in protein expression of PPARγ and C/EBPα, the master regulators of adipocyte differentiation and in DNA binding of C/EBPβ and C/EBPδ. Moreover, luteolin was rapidly incorporated and accumulated in 3T3-L1 adipocytes. Thus, luteolin is an attractive compound for the prevention of TCDD-induced wasting syndrome.
authors.affiliation: Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan. Electronic address: ashida@kobe-u.ac.jp.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Ashida
authors.affiliation: Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan.
authors.forename: Kiyonari
authors.initials: K
authors.lastname: Harada
authors.affiliation: Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan.
authors.forename: Sakiho
authors.initials: S
authors.lastname: Mishima
authors.affiliation: Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan.
authors.forename: Takakazu
authors.initials: T
authors.lastname: Mitani
authors.affiliation: Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Yamashita
authors.affiliation: Department of Environmental Toxicology, University of California Davis, One Shields Avenue, CA 95616, USA.
authors.forename: Fumio
authors.initials: F
authors.lastname: Matsumura
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000378:metabolism; D051743:CCAAT-Enhancer-Binding Protein-delta / Q000378:metabolism; D022762:CCAAT-Enhancer-Binding Proteins / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D050356:Lipid Metabolism; D047311:Luteolin / Q000494:pharmacology*; D051379:Mice; D047495:PPAR gamma / Q000378:metabolism; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*; D018336:Receptors, Aryl Hydrocarbon / Q000378:metabolism; D019282:Wasting Syndrome
chemical_list: D022782:CCAAT-Enhancer-Binding Protein-beta; D022762:CCAAT-Enhancer-Binding Proteins; C530718:CEBPA protein, mouse; D047495:PPAR gamma; D000072317:Polychlorinated Dibenzodioxins; D018336:Receptors, Aryl Hydrocarbon; D051743:CCAAT-Enhancer-Binding Protein-delta; D004247:DNA; D047311:Luteolin
keywords: Adipocyte differentiation; AhR; C/EBPs; PPARγ; TCDD; Wasting syndrome