A Novel Allosteric Inhibitor of Macrophage Migration Inhibitory Factor (MIF)
A Novel Allosteric Inhibitor of Macrophage Migration Inhibitory Factor (MIF)
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DOI：
10.1074/jbc.m112.385583
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发表时间：
2012-08-31
影响因子：
4.8
通讯作者：
Anthony, Karen G.
中科院分区：
文献类型：
--
作者：
Bai, Fengwei;Asojo, Oluwatoyin A.;Anthony, Karen G.
巨噬细胞迁移抑制因子（MIF）是一种催化细胞因子，也是炎症通路的上游介质。 MIF 具有广泛的调节特性，其失调与多种免疫疾病的病理学有关。事实证明，用小分子抑制 MIF 活性在许多疾病模型中是有益的。已知的小分子 MIF 抑制剂通常结合在 MIF 三聚体的互变异构酶位点，通常共价修饰催化脯氨酸。变构 MIF 抑制剂，特别是那些通过非共价相互作用与蛋白质结合的抑制剂，可以揭示阻断 MIF 活性以获得治疗效果的新方法，并作为化学探针来阐明 MIF 多种调节特性的结构基础。在这项研究中，我们报告了一种新型变构 MIF 抑制剂的鉴定和功能表征。通过高通量筛选工作鉴定出，这种名为 p425 的磺化偶氮化合物强烈抑制 MIF 互变异构化 4-羟苯基丙酮酸的能力。此外，p425 阻断 MIF 与其受体 CD74 的相互作用，并干扰细胞因子的促炎活性。结构研究揭示了 p425 的独特结合模式，单个抑制剂分子占据两个 MIF 三聚体的界面。该抑制剂主要通过疏水相互作用在蛋白质表面结合 MIF，疏水相互作用通过与来自三个不同单体的四个高度特异性残基的氢键作用来稳定。 p425 结合模式揭示了一种独特的方法来阻断细胞因子的活性，从而为 MIF 相关疾病提供潜在的治疗益处。
Macrophage migration inhibitory factor (MIF) is a catalytic cytokine and an upstream mediator of the inflammatory pathway. MIF has broad regulatory properties, dysregulation of which has been implicated in the pathology of multiple immunological diseases. Inhibition of MIF activity with small molecules has proven beneficial in a number of disease models. Known small molecule MIF inhibitors typically bind in the tautomerase site of the MIF trimer, often covalently modifying the catalytic proline. Allosteric MIF inhibitors, particularly those that associate with the protein by noncovalent interactions, could reveal novel ways to block MIF activity for therapeutic benefit and serve as chemical probes to elucidate the structural basis for the diverse regulatory properties of MIF. In this study, we report the identification and functional characterization of a novel allosteric MIF inhibitor. Identified from a high throughput screening effort, this sulfonated azo compound termed p425 strongly inhibited the ability of MIF to tautomerize 4-hydroxyphenyl pyruvate. Furthermore, p425 blocked the interaction of MIF with its receptor, CD74, and interfered with the pro-inflammatory activities of the cytokine. Structural studies revealed a unique mode of binding for p425, with a single molecule of the inhibitor occupying the interface of two MIF trimers. The inhibitor binds MIF mainly on the protein surface through hydrophobic interactions that are stabilized by hydrogen bonding with four highly specific residues from three different monomers. The mode of p425 binding reveals a unique way to block the activity of the cytokine for potential therapeutic benefit in MIF-associated diseases.