Mycobacteria directly induce cytoskeletal rearrangements for macrophage spreading and polarization through TLR2-dependent PI3K signaling
Mycobacteria directly induce cytoskeletal rearrangements for macrophage spreading and polarization through TLR2-dependent PI3K signaling
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DOI：
10.1189/jlb.0106066
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发表时间：
2006-12-01
影响因子：
5.5
通讯作者：
Da Silva, Wilmar D.
中科院分区：
文献类型：
--
作者：
Lasunskaia, Elena B.;Campos, Mariana N. N.;Da Silva, Wilmar D.
巨噬细胞的迁移和粘附对于控制分枝杆菌感染非常重要，并且严重依赖于细胞骨架的重组。分枝杆菌引起快速的形态变化，如细胞扩散，这是一个与外渗和迁移期间巨噬细胞形状的体内变化相关的过程。在这项研究中，我们研究了BCG分枝杆菌诱导的信号传导事件，导致巨噬细胞骨架重排，采用特定的药理学抑制剂来抑制已知由感染引起的不同激酶途径。活的或裂解的分枝杆菌，以及纯化的细胞壁脂蛋白p19，TLR 2激动剂，诱导RAW264.7细胞延长肌动蛋白丰富的伪足，赋予径向扩展3小时内，导致后来持续的细胞极化。BCG诱导磷脂酰肌醇3-激酶（PI 3 K）的快速活化，所述活化被募集到活化的TLR 2受体。TLR 2中和抗体抑制p19诱导的巨噬细胞扩散和PI 3 K活化。此外，BCG诱导TLR 2表达小鼠骨髓来源的巨噬细胞的扩散和极化，与TLR 2敲除小鼠相反。MEK 1/ERK、p38 MAPK和NF-κ B B活化对观察到的早期细胞骨架重排均不重要，尽管已知抑制这些途径可抑制活化巨噬细胞的趋化因子分泌。用相应抗体阻断β 2-整联蛋白可抑制巨噬细胞扩散和极化，但对伪足突起没有影响，这表明在导致运动表型的PI 3 K依赖性信号传导途径中整联蛋白介导的粘附的下游位置。所获得的数据表明，分枝杆菌对巨噬细胞形状的直接影响可能是通过TLR 2依赖性PI 3 K激活介导的。
Macrophage migration and adhesion are important for the control of mycobacterial infection and are critically dependent on the reorganization of the cytoskeleton. Mycobacteria elicit rapid morphological changes, such as cell spreading, a process relevant to in vivo changes of macrophage shape during extravasation and migration. In this study, we investigated the BCG mycobacteria-induced signaling events leading to macrophage cytoskeletal rearrangements employing specific pharmacological inhibitors to suppress distinct kinase pathways known to be elicited by infection. Viable or lysed mycobacteria, as well as purified cell wall lipoprotein p19, TLR2 agonist, induced RAW264.7 cells to extend actin-rich pseudopods, which impart radial spreading within 3 h, leading later to persistent cell polarization. BCG induced rapid activation of phosphatidylinositol 3-kinase, PI3K, activation that was recruited to the activated TLR2 receptor. TLR2-neutralizing antibody inhibited macrophage spreading and PI3K activation induced by p19. Additionally, BCG induced spreading and polarization of bone marrow-derived macrophages from TLR2- expressing mice in contrast to their TLR2-knockout counterparts. Neither MEK1/ERK, p38 MAPK, nor NF-kappa B activation were important for the early cytoskeletal rearrangements observed, although suppression of these pathways is known to inhibit chemokine secretion by activated macrophages. B2-integrins blockade with a corresponding antibody inhibited macrophage spreading and polarization but had no effect on pseudopodia protrusions demonstrating the downstream position of integrin-mediated adhesion in PI3K-dependent signaling pathway leading to the motility phenotype. The obtained data demonstrate that the direct effect of mycobacteria on macrophage shape might be mediated through TLR2-dependent PI3K activation.