Isorhamnetin-induced anti-adipogenesis is mediated by stabilization of beta-catenin protein.
OBJECTIVE
Previous studies have shown that isorhamnetin has anti-adipogenic effects in mouse 3T3-L1 cells. This study was conducted to elucidate the inhibitory mechanisms of isorhamnetin during adipogenic differentiation of human adipose tissue-derived stem cells (hAMSCs).


METHODS
The effect of isorhamnetin on adipogenic differentiation of hAMSCs was quantified by Oil Red O staining and a triglyceride assay. In addition, real-time PCR and Western blot were used to determine the expression of adipogenesis-related genes.


RESULTS
Isorhamnetin inhibited the adipocyte differentiation of hAMSCs. Additionally, when the effects of Wnt antagonists that promote adipogenesis were evaluated, isorhamnetin was found to down-regulate the mRNA levels of sFRP1 and Dkk1, but had no effect on the mRNA levels of sFRP2, sFRP3, sFRP4 and Dkk3. Isorhamnetin also inhibited the expression of Wnt receptor and co-receptor genes. Furthermore, isorhamnetin increased the protein levels of beta-catenin, an effector molecule of Wnt signaling, but had no effect on the mRNA levels of beta-catenin. The phosphorylation level of GSK 3beta was also increased by isorhamnetin. These results were confirmed by the fact that the expression of c-myc, cyclin D1 and PPARdelta, which are target genes of beta-catenin, was upregulated by isorhamnetin. Moreover, isorhamnetin reduced the mRNA expression levels of C/EBPalpha and PPARgamma, which are known to be inhibited by c-myc or by cyclin D1 and PPARdelta, respectively.


CONCLUSIONS
Our results indicate that isorhamnetin inhibits the adipogenic differentiation of hAMSCs and that its mechanisms are mediated by the stabilization of beta-catenin.
Lee
Jongsung
J
Biospectrum Life Science Institute, 101-701 SK Ventium, 522 Dangjung Dong, Gunpo City, 435-833 Gyunggi Do, Republic of Korea.
Lee
Jienny
J
Jung
Eunsun
E
Hwang
Wangtaek
W
Kim
Yeong-Shik
YS
Park
Deokhoon
D
D041721:3T3-L1 Cells; D050156:Adipogenesis / Q000187:drug effects*; D000273:Adipose Tissue / Q000166:cytology; D000818:Animals; D001391:Azo Compounds; D015153:Blotting, Western; D002454:Cell Differentiation / Q000187:drug effects; D044948:Flavonols / Q000494:pharmacology*; D006801:Humans; D007202:Indicators and Reagents; D051379:Mice; D011794:Quercetin / Q000031:analogs & derivatives; D012313:RNA / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013234:Stem Cells / Q000187:drug effects; D014280:Triglycerides / Q000378:metabolism; D051153:Wnt Proteins / Q000037:antagonists & inhibitors; D051176:beta Catenin / Q000502:physiology*
D001391:Azo Compounds; D044948:Flavonols; D007202:Indicators and Reagents; D014280:Triglycerides; D051153:Wnt Proteins; D051176:beta Catenin; C047368:3-methylquercetin; D012313:RNA; D011794:Quercetin; C011049:oil red O