Eps8 Protein Facilitates Phagocytosis by Increasing TLR4-MyD88 Protein Interaction in Lipopolysaccharide-stimulated Macrophages
Eps8 Protein Facilitates Phagocytosis by Increasing TLR4-MyD88 Protein Interaction in Lipopolysaccharide-stimulated Macrophages
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DOI：
10.1074/jbc.m112.340935
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发表时间：
2012-05-25
影响因子：
4.8
通讯作者：
Leu, Tzeng-Horng
中科院分区：
文献类型：
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作者：
Chen, Yen-Jen;Hsieh, Ming-Yu;Leu, Tzeng-Horng
Toll 样受体 (TLR) 在巨噬细胞吞噬作用中至关重要，而巨噬细胞吞噬作用在宿主先天免疫反应中至关重要。然而，详细机制尚未完全确定。在这里，我们证明了 LPS 处理的巨噬细胞中 Src 和 Eps8 的诱导是 TLR4 和 MyD88 依赖性的，并且它们的减弱减少了 LPS 促进的吞噬作用。共聚焦显微镜表明 Eps8 和 TLR4 在胞质溶胶和吞噬体中共定位。一致的是，无论 LPS 刺激如何，Eps8 和 TLR4 都存在于同一免疫复合物中。通过eps8 siRNA或过表达pleckstrin同源结构域截短的Eps8（即261-p97（Eps8））抑制这种复合物的形成，减少了LPS诱导的TLR4-MyD88相互作用以及随后的Src、粘着斑激酶和p38 MAPK的激活。重要的是，Eps8 的减弱削弱了巨噬细胞的杀菌能力。因此，Eps8 是 LPS 刺激的 TLR4-MyD88 相互作用的关键调节因子，并有助于巨噬细胞的吞噬作用。
Toll-like receptors (TLRs) are crucial in macrophage phagocytosis, which is pivotal in host innate immune response. However, the detailed mechanism is not fully defined. Here, we demonstrated that the induction of Src and Eps8 in LPS-treated macrophages was TLR4- and MyD88-dependent, and their attenuation reduced LPS-promoted phagocytosis. Confocal microscopy indicated the colocalization of Eps8 and TLR4 in the cytosol and at the phagosome. Consistently, both Eps8 and TLR4 were present in the same immunocomplex regard-less of LPS stimulation. Inhibition of this complex formation by eps8 siRNA or overexpression of pleckstrin homology domain-truncated Eps8 (i.e. 261-p97(Eps8)) decreased LPS-induced TLR4-MyD88 interaction and the following activation of Src, focal adhesion kinase, and p38 MAPK. Importantly, attenuation of Eps8 impaired the bacterium-killing ability of macrophages. Thus, Eps8 is a key regulator of the LPS-stimulated TLR4-MyD88 interaction and contributes to macrophage phagocytosis.