Bixin regulates mRNA expression involved in adipogenesis and enhances insulin sensitivity in 3T3-L1 adipocytes through PPARgamma activation.
Insulin resistance is partly due to suppression of insulin-induced glucose uptake into adipocytes. The uptake is dependent on adipocyte differentiation, which is controlled at mRNA transcription level. The peroxisome proliferator-activated receptor (PPAR), a ligand-regulated nuclear receptor, is involved in the differentiation. Many food-derived compounds serve as ligands to activate or inactivate PPAR. In this study, we demonstrated that bixin and norbixin (annatto extracts) activate PPARgamma by luciferase reporter assay using GAL4-PPAR chimera proteins. To examine the effects of bixin on adipocytes, 3T3-L1 adipocytes were treated with bixin or norbixin. The treatment induced mRNA expression of PPARgamma target genes such as adipocyte-specific fatty acid-binding protein (aP2), lipoprotein lipase (LPL), and adiponectin in differentiated 3T3-L1 adipocytes and enhanced insulin-dependent glucose uptake. The observations indicate that bixin acts as an agonist of PPARgamma and enhances insulin sensitivity in 3T3-L1 adipocytes, suggesting that bixin is a valuable food-derived compound as a PPAR ligand to regulate lipid metabolism and to ameliorate metabolic syndrome.
Takahashi
Nobuyuki
N
Laboratory of Molecular Function of Food, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji 611-0011, Japan.
Goto
Tsuyoshi
T
Taimatsu
Aki
A
Egawa
Kahori
K
Katoh
Sota
S
Kusudo
Tatsuya
T
Sakamoto
Tomoya
T
Ohyane
Chie
C
Lee
Joo-Young
JY
Kim
Young-Il
YI
Uemura
Taku
T
Hirai
Shizuka
S
Kawada
Teruo
T
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000187:drug effects* / Q000378:metabolism; D050156:Adipogenesis / Q000187:drug effects*; D000818:Animals; D002338:Carotenoids / Q000494:pharmacology*; D017930:Genes, Reporter / Q000187:drug effects; D005947:Glucose / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance; D050356:Lipid Metabolism / Q000187:drug effects; D008156:Luciferases / Q000235:genetics; D051379:Mice; D047495:PPAR gamma / Q000819:agonists*; D012333:RNA, Messenger / Q000096:biosynthesis
D007328:Insulin; D047495:PPAR gamma; D012333:RNA, Messenger; D002338:Carotenoids; C004588:bixin; C099823:norbixin; D008156:Luciferases; D005947:Glucose