Shen Yu-fan, Zhang Xue, Wang Ying, Cao Fan-fan, Uzan Georges, Peng Bin, Zhang Deng-hai
Department of Clinical Laboratory Diagnostics, Postgraduate Education College, Ningxia Medical University, Yinchuan 750004, Ningxia Hui Autonomous Region, China.
Sino-French Cooperative Central Laboratory, Shanghai Gongli Hospital, Second Military Medical University, Shanghai 200135, China.
J Integr Med. 2016 May;14(3):203-8. doi: 10.1016/S2095-4964(16)60257-1.
Celastrol has been established as a nuclear factor-κB (NF-κB) activation inhibitor; however, the exact mechanism behind this action is still unknown. Using text-mining technology, the authors predicted that interleukin-1 receptor-associated kinases (IRAKs) are potential celastrol targets, and hypothesized that targeting IRAKs might be one way that celastrol inhibits NF-κB. This is because IRAKs are key molecules for some crucial pathways to activate NF-κB (e.g., the interleukin-1 receptor (IL-1R)/Toll-like receptor (TLR) superfamily).
The human hepatocellular cell line (HepG2) treated with palmitic acid (PA) was used as a model for stimulating TLR4/NF-κB activation, in order to observe the potential effects of celastrol in IRAK regulation and NF-κB inhibition. The transfection of small interfering RNA was used for down-regulating TLR4, IRAK1 and IRAK4, and the Western blot method was used to detect changes in the protein expressions.
The results showed that celastrol could effectively inhibit PA-caused TLR4-dependent NF-κB activation in the HepG2 cells; PA also activated IRAKs, which were inhibited by celastrol. Knocking down IRAKs abolished PA-caused NF-κB activation.
The results for the first time show that targeting IRAKs is one way in which celastrol inhibits NF-κB activation.
雷公藤红素已被证实为一种核因子-κB（NF-κB）激活抑制剂；然而，这一作用背后的确切机制仍不清楚。通过文本挖掘技术，作者预测白细胞介素-1受体相关激酶（IRAKs）是雷公藤红素的潜在靶点，并假设靶向IRAKs可能是雷公藤红素抑制NF-κB的一种方式。这是因为IRAKs是激活NF-κB的一些关键信号通路（如白细胞介素-1受体（IL-1R）/Toll样受体（TLR）超家族）中的关键分子。
以棕榈酸（PA）处理的人肝癌细胞系（HepG2）作为刺激TLR4/NF-κB激活的模型，以观察雷公藤红素在IRAK调节和NF-κB抑制方面的潜在作用。采用小干扰RNA转染下调TLR4、IRAK1和IRAK4，并运用蛋白质印迹法检测蛋白表达的变化。
结果表明，雷公藤红素可有效抑制PA诱导的HepG2细胞中TLR4依赖的NF-κB激活；PA还激活了IRAKs，而雷公藤红素可抑制这一激活。敲低IRAKs可消除PA诱导的NF-κB激活。
研究结果首次表明，靶向IRAKs是雷公藤红素抑制NF-κB激活的一种方式。
