Functional Food Technology Research Group, Korea Food Research Institute, 516, Baekhyn-dong, Seongnam-si, Gyeonggi-do 463-746, Republic of Korea.
BMC Complement Altern Med. 2013 Aug 6;13:207. doi: 10.1186/1472-6882-13-207.
The naphthoquinone pigment, shikonin, is a major component of Lithospermum erythrorhizon and has been shown to have various biological functions, including antimicrobial, anti-inflammatory, and antitumor effects. In this study, we investigated the effect of shikonin on adipocyte differentiation and its mechanism of action in 3T3-L1 cells.
To investigate the effects of shikonin on adipocyte differentiation, 3T3-L1 cells were induced to differentiate using 3-isobutyl-1-methylzanthine, dexamethasone, and insulin (MDI) for 8 days in the presence of 0-2 μM shikonin. Oil Red O staining was performed to determine the lipid accumulation in 3T3-L1 cells. To elucidate the anti-adipogenic mechanism of shikonin, adipogenic transcription factors, the phosphorylation levels of ERK, and adipogenic gene expression were analyzed by Western blotting and quantitative real-time PCR. To further confirm that shikonin inhibits adipogenic differentiation through downregulation of ERK 1/2 activity, 3T3-L1 cells were treated with shikonin in the presence of FGF-2, an activator, or PD98059, an inhibitor, of the ERK1/2 signaling pathway.
Shikonin effectively suppressed adipogenesis and downregulated the protein levels of 2 major transcription factors, PPARγ and C/EBPα, as well as the adipocyte specific gene aP2 in a dose-dependent manner. qRT-PCR analysis revealed that shikonin inhibited mRNA expression of adipogenesis-related genes, such as PPARγ, C/EBPα, and aP2. Adipocyte differentiation was mediated by ERK 1/2 phosphorylation, which was confirmed by pretreatment with PD98059 (an ERK 1/2 inhibitor) or FGF-2 (an ERK 1/2 activator). The phosphorylation of ERK1/2 during the early stages of adipogenesis in 3T3-L1 cells was inhibited by shikonin. We also confirmed that FGF-2-stimulated ERK 1/2 activity was attenuated by shikonin.
These results demonstrate that shikonin inhibits adipogenic differentiation via suppression of the ERK signaling pathway during the early stages of adipogenesis.
萘醌色素紫草素是紫草的主要成分，具有多种生物学功能，包括抗菌、抗炎和抗肿瘤作用。在这项研究中，我们研究了紫草素对脂肪细胞分化的影响及其在 3T3-L1 细胞中的作用机制。
为了研究紫草素对脂肪细胞分化的影响，我们使用 3-异丁基-1-甲基黄嘌呤、地塞米松和胰岛素（MDI）诱导 3T3-L1 细胞分化 8 天，同时加入 0-2 μM 的紫草素。用油红 O 染色法测定 3T3-L1 细胞中的脂质积累。为了阐明紫草素的抗脂肪生成机制，我们通过 Western blot 和定量实时 PCR 分析脂肪生成转录因子、ERK 的磷酸化水平和脂肪生成基因的表达。为了进一步证实紫草素通过下调 ERK1/2 活性抑制脂肪生成分化，我们在 FGF-2（ERK1/2 信号通路的激活剂）或 PD98059（ERK1/2 抑制剂）存在的情况下用紫草素处理 3T3-L1 细胞。
紫草素有效抑制脂肪生成，并呈剂量依赖性地下调主要转录因子 PPARγ 和 C/EBPα以及脂肪细胞特异性基因 aP2 的蛋白水平。qRT-PCR 分析显示，紫草素抑制脂肪生成相关基因如 PPARγ、C/EBPα 和 aP2 的 mRNA 表达。脂肪细胞分化由 ERK 1/2 磷酸化介导，这通过用 PD98059（ERK 1/2 抑制剂）或 FGF-2（ERK 1/2 激活剂）预处理得到证实。在 3T3-L1 细胞脂肪生成的早期阶段，ERK1/2 的磷酸化被紫草素抑制。我们还证实，FGF-2 刺激的 ERK 1/2 活性被紫草素减弱。
这些结果表明，紫草素通过抑制脂肪生成早期阶段的 ERK 信号通路来抑制脂肪生成分化。
