Obacunone causes sustained expression of MKP-1 thus inactivating p38 MAPK to suppress pro-inflammatory mediators through intracellular MIF
Obacunone causes sustained expression of MKP-1 thus inactivating p38 MAPK to suppress pro-inflammatory mediators through intracellular MIF
复制标题
Obacunone 引起 MKP-1 持续表达，从而使 p38 MAPK 失活，从而通过细胞内 MIF 抑制促炎介质
DOI：
10.1002/jcb.26248
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发表时间：
2018-01-01
影响因子：
4
通讯作者：
Qi, Yun
中科院分区：
文献类型：
--
作者：
Gao, Yuan;Hou, Rui;Qi, Yun
欧诺酮是一种具有多种药理活性的高氧三萜化合物。在本研究中，我们探讨了其对lps活化巨噬细胞的抗炎作用及其机制。我们的数据显示，OBA在转录和翻译水平上能有效降低促炎介质（如NO、IL-6、IL-1和MCP-1），而无细胞毒性。机制研究表明，OBA通过稳定丝裂原活化蛋白激酶磷酸酶1 (MKP-1) mRNA，从而延长MKP-1蛋白的表达时间，显著抑制p38介导的AP-1信号转导。接下来，我们使用计算目标钓鱼技术来预测OBA可能的目标。只有一个潜在的靶点，巨噬细胞迁移抑制因子（MIF）被提出。实验也证实了OBA与MIF之间的相互作用。通过使用抗小鼠MIF抗体，细胞外MIF （exMIF）被中和。我们的研究结果表明，自分泌MIF对促炎介质的产生有轻微的影响。相应地，OBA的抗炎活性也不受影响。因此，我们在RAW 264.7细胞中敲除MIF基因，获得了稳定的MIF缺陷细胞MIF(-)，其中OBA对p38磷酸化、AP-1激活和促炎介质产生响应LPS的影响几乎消失。与MIF（+）细胞相比，MIF（-）细胞的MKP-1蛋白表达时间明显延长。我们认为，OBA通过抑制细胞内MIF （inMIF）调控MKP-1/p38/AP-1通路发挥其抗炎作用。我们的研究结果还提供了一系列证据，表明抑制inMIF而不是exMIF可能成为炎症的新靶点。
Obacunone (OBA) is a highly oxygenated triterpenoid with various pharmacological activities. In this study, we explored its anti-inflammatory effect and underlying mechanisms in LPS-activated macrophages. Our data showed that OBA potently decreased pro-inflammatory mediators (eg, NO, IL-6, IL-1, and MCP-1) at the transcriptional and translational levels without cytotoxicity. A mechanism study showed that OBA significantly suppressed p38-mediated AP-1 signaling by stabilizing the mRNA of mitogen-activated protein kinase phosphatase 1 (MKP-1), thus prolonging the expression time of the MKP-1 protein. Next, we used computational target-fishing technology to predict the possible target of OBA. Only one potential target, macrophage migration inhibitory factor (MIF), was presented. Experimentally, the interaction between OBA and MIF was also confirmed. By using an anti-mouse MIF antibody, extracellular MIF (exMIF) was neutralized. Our results showed that autocrine MIF had slight influence on the pro-inflammatory mediator production. Correspondingly, the anti-inflammatory activity of OBA was also not affected. Accordingly, we knocked down the MIF gene in RAW 264.7 cells and obtained stable MIF deficient cells MIF(-), in which the effects of OBA on p38 phosphorylation, AP-1 activation, and pro-inflammatory mediator production in response to LPS nearly disappeared. In contrast to MIF(+) cells, the MKP-1 protein expression time of the MIF(-) cells was markedly prolonged. We conclude that OBA exerts its anti-inflammatory effect by targeting intracellular MIF (inMIF) inhibition to regulate the MKP-1/p38/AP-1 pathway. Our findings also provide a chain of evidence that the inhibition of inMIF, rather than exMIF, may become a novel target for inflammation.