Effects of Vitexin from Mung Bean on 3T3-L1 Adipocyte Differentiation and Regulation According to Adipocytokine Secretion

녹두의 Vitexin이 비만전구세포에서 세포분화 및 아디포사이토카인 분비능에 미치는 영향

Obesity is an important issue worldwide as it may associated with increased prevalence of metabolic diseases. Mung bean is known as a functional food for decreasing the glycemic index and lipid profile of plasma. The purpose of this study was to investigate the anti-obesity effects of vitexin from mung bean on the regulation of adipocyte differentiation and adipocytokine secretion. When 3T3-L1 adipocytes were treated with vitexin from days 0 to 14 at various levels of 25, 50, 100, and $200{\mu}M$, there was no change in cell viability. Vitexin treatment at 50, 100, and $200{\mu}M$ decreased triacylglycerol levels in cells, but only $100{\mu}M$ vitexin induced lipolysis. At $200{\mu}M$ of vitexin, phosphorylation of p38 and ERK, which causes secretion of inflammatory adipocytokines, was depressed, whereas there was an increase in expression of $PPAR{\gamma}$, the key regulator of adipocyte differentiation. Phosphorylation of AMPK increased at $100{\mu}M$ vitexin. TNF-${\alpha}$ and aP2 mRNA expression increased at $25{\mu}M$ vitexin, whereas only TNF-${\alpha}$ mRNA expression increased at $200{\mu}M$ vitexin. Further, the mRNA levels of TNF-${\alpha}$ and aP2 decreased at other concentrations in a dose-dependent manner. Since we observed that mRNA expression of C/EBP, SREBP1, and $PPAR{\gamma}$ did not change upon vitexin treatment, our future studies will investigate other genes such as mTOR, which is related with apoptosis signaling, or SIRT1, which is associated with inhibition of adipogenesis. Our results indicate that vitexin at concentrations between 100 and $200{\mu}M$ is suitable in vivo for the development of mung bean as an anti-obesity therapy or functional food.

본 연구는 녹두묵을 이용한 항비만 임상선행연구를 바탕으로 녹두에 풍부한 vitexin의 항비만 효과의 기작을 살펴보고자 하였다. 녹두 vitexin은 $200{\mu}M$ 농도까지 3T3-L1 지방 전구세포의 독성효과는 없었으며 50, 100, $200{\mu}M$ 농도에서 지방합성이 억제되었고 $100{\mu}M$ 농도에서 지방분해효과로 추측할 수 있는 결과가 나타났다. 또한 $200{\mu}M$에서 염증성 아디포사이토카인 유전자발현을 증폭시키는 상위신호체계(p38, ERK)가 억제된 반면 AMPK의 경우는 $100{\mu}M$ 농도까지 증가하였고 $PPAR{\gamma}$ 단백질 발현도 $200{\mu}M$에서 증폭하였으며 TNF-${\alpha}$와 aP2 mRNA 발현은 $25{\mu}M$에 증가하였다가 감소하였다. 이러한 결과를 바탕으로 결론을 내리면 vitexin $100{\sim}200{\mu}M$ 사이의 농도가 항비만 기작을 규명하는 in vivo 실험을 위한 적절한 농도로 여겨진다. 그러나 본 연구에서는 vitexin 처리에 따른 C/EBP, SREBP1, $PPAR{\gamma}$ mRNA 농도의 변화는 관찰되지 않아 3T3-L1 세포자살(apoptosis) 신호체계 및 mTOR와의 연계성체계 혹은 기타 adipogenesis 억제 유전자로 SIRT1 등의 연구가 향후에 더 필요할 것으로 사료된다.