title: Mono(2-ethylhexyl)phthalate accumulation disturbs energy metabolism of fat cells.
abstract: Phthalates are lipophilic and tend to accumulate in adipose tissue, an important regulator of energy balance and glucose homeostasis. The study aimed to determine whether cellular phthalate accumulation influenced fat cell energy metabolism. Following a 3-day treatment with adipogenesis-inducing medium and a 2-day treatment with adipogenesis-maintaining medium, 3T3-L1 cells differentiated into adipocytes in the presence of a phthalate at a clinically relevant concentration (30-300 μM) for another 6 days. Two phthalates, di(2-ethylhexyl)phthalate and di-n-butylphthalate, and their metabolites, mono(2-ethylhexyl)phthalate (MEHP) and mono-n-butylphthalate, were used here. The phthalate treatments caused no marked effect on cytotoxicity and adipogenesis. Only the MEHP-treated adipocytes were found having smaller lipid droplets; MEHP accumulated in cells in a dose- and time-dependent manner. The MEHP-treated adipocytes exhibited significant increases in lipolysis and glucose uptake; quantitative real-time polymerase chain reaction (qPCR) analysis revealed correlated changes in expression of marker genes involved in adipogenesis, lipid metabolism, and glucose uptake. Analysis of oxygen consumption rate (a mitochondrial respiration indicator) and extracellular acidification rate (a glycolysis indicator) indicated a higher energy metabolism in the adipocytes. qPCR analysis of critical genes involved in mitochondrial biogenesis and/or energy metabolism showed that expression of peroxisome proliferator-activated receptor γ coactivator-1α, sirtuin 3, and protein kinase A were significantly enhanced in the MEHP-treated adipocytes. In vitro evidence of MEHP impacts on lipolysis, glucose uptake/glycolysis, and mitochondrial respiration/biogenesis demonstrates that MEHP accumulation disturbs energy metabolism of fat cells.
authors.affiliation: Division of Environmental Health and Occupational Medicine, National Health Research Institutes, 35 Keyan Road, Zhunan, Miaoli, 350, Taiwan.
authors.forename: Huai-chih
authors.initials: HC
authors.lastname: Chiang
authors.affiliation: Division of Environmental Health and Occupational Medicine, National Health Research Institutes, 35 Keyan Road, Zhunan, Miaoli, 350, Taiwan.
authors.forename: Ya-Ting
authors.initials: YT
authors.lastname: Kuo
authors.affiliation: Division of Environmental Health and Occupational Medicine, National Health Research Institutes, 35 Keyan Road, Zhunan, Miaoli, 350, Taiwan.
authors.forename: Chih-Che
authors.initials: CC
authors.lastname: Shen
authors.affiliation: Division of Environmental Health and Occupational Medicine, National Health Research Institutes, 35 Keyan Road, Zhunan, Miaoli, 350, Taiwan.
authors.forename: Yi-Hua
authors.initials: YH
authors.lastname: Lin
authors.affiliation: Division of Environmental Health and Occupational Medicine, National Health Research Institutes, 35 Keyan Road, Zhunan, Miaoli, 350, Taiwan.
authors.forename: Shu-Li
authors.initials: SL
authors.lastname: Wang
authors.affiliation: Division of Environmental Health and Occupational Medicine, National Health Research Institutes, 35 Keyan Road, Zhunan, Miaoli, 350, Taiwan. tctsou@nhri.org.tw.
authors.forename: Tsui-Chun
authors.initials: TC
authors.lastname: Tsou
mesh_terms: D041721:3T3-L1 Cells / Q000187:drug effects / Q000378:metabolism; D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D004051:Diethylhexyl Phthalate / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000633:toxicity; D004734:Energy Metabolism / Q000187:drug effects*; D005786:Gene Expression Regulation / Q000187:drug effects; D005947:Glucose / Q000378:metabolism; D066292:Lipid Droplets / Q000187:drug effects / Q000378:metabolism; D008066:Lipolysis / Q000187:drug effects; D051379:Mice
chemical_list: D004051:Diethylhexyl Phthalate; C016599:mono-(2-ethylhexyl)phthalate; D005947:Glucose
keywords: Adipocytes; Glucose uptake; Lipolysis; MEHP; Mitochondria; Phthalates