The small molecule indirubin-3'-oxime activates Wnt/β-catenin signaling and inhibits adipocyte differentiation and obesity.
OBJECTIVE
Activation of the Wnt/β-catenin signaling pathway inhibits adipogenesis by maintaining preadipocytes in an undifferentiated state. We investigated the effect of indirubin-3'-oxime (I3O), which was screened as an activator of the Wnt/β-catenin signaling, on inhibiting the preadipocyte differentiation in vitro and in vivo.


METHODS
3T3L1 preadipocytes were differentiated with 0, 4 or 20 μM of I3O. The I3O effect on adipocyte differentiation was observed by Oil-red-O staining. Activation of Wnt/β-catenin signaling in I3O-treated 3T3L1 cells was shown using immunocytochemical and immunoblotting analyses for β-catenin. The regulation of adipogenic markers was analyzed via real-time reverse transcription-PCR (RT-PCR) and immunoblotting analyses. For the in vivo study, mice were divided into five different dietary groups: chow diet, high-fat diet (HFD), HFD supplemented with I3O at 5, 25 and 100 mg kg(-1). After 8 weeks, adipose and liver tissues were excised from the mice and subject to morphometry, real-time RT-PCR, immunoblotting and histological or immunohistochemical analyses. In addition, adipokine and insulin concentrations in serum of the mice were accessed by enzyme-linked immunosorbent assay.


RESULTS
Using a cell-based approach to screen a library of pharmacologically active small molecules, we identified I3O as a Wnt/β-catenin pathway activator. I3O inhibited the differentiation of 3T3-L1 cells into mature adipocytes and decreased the expression of adipocyte markers, CCAAT/enhancer-binding protein α and peroxisome proliferator-activated receptor γ, at both mRNA and protein levels. In vivo, I3O inhibited the development of obesity in HFD-fed mice by attenuating HFD-induced body weight gain and visceral fat accumulation without showing any significant toxicity. Factors associated with metabolic disorders such as hyperlipidemia and hyperglycemia were also improved by treatment of I3O.


CONCLUSIONS
Activation of the Wnt/β-catenin signaling pathway can be used as a therapeutic strategy for the treatment of obesity and metabolic syndrome and implicates I3O as a candidate anti-obesity agent.
1] Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea [2] Translational Research Center for Protein Function Control, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea.
O M
OM
Choi
1] Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea [2] Translational Research Center for Protein Function Control, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea.
Y-H
YH
Cho
Department of Food and Nutrition, Yonsei University, Seoul, Korea.
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S
Choi
1] Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea [2] Translational Research Center for Protein Function Control, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea.
S-H
SH
Lee
1] Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea [2] Translational Research Center for Protein Function Control, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea.
S H
SH
Seo
1] Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea [2] Translational Research Center for Protein Function Control, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea.
H-Y
HY
Kim
1] Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea [2] Translational Research Center for Protein Function Control, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea.
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G
Han
1] Translational Research Center for Protein Function Control, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea [2] Department of Molecular Biology, College of Natural Science, Pusan National University, Pusan, Korea.
D S
DS
Min
Department of Food and Nutrition, Yonsei University, Seoul, Korea.
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T
Park
1] Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea [2] Translational Research Center for Protein Function Control, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea.
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KY
Choi
D041721:3T3-L1 Cells / Q000187:drug effects; D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism; D050156:Adipogenesis / Q000187:drug effects*; D000818:Animals; D019440:Anti-Obesity Agents / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects; D059305:Diet, High-Fat; D007211:Indoles / Q000494:pharmacology*; D008297:Male; D008516:Medicine, Chinese Traditional; D024821:Metabolic Syndrome / Q000188:drug therapy / Q000378:metabolism*; D051379:Mice; D009765:Obesity / Q000188:drug therapy / Q000378:metabolism*; D010091:Oximes / Q000494:pharmacology*; D016133:Polymerase Chain Reaction / Q000379:methods; D060449:Wnt Signaling Pathway / Q000187:drug effects*
D019440:Anti-Obesity Agents; D007211:Indoles; D010091:Oximes; C474021:indirubin-3'-monoxime