Membrane Ruffles Capture C3bi-opsonized Particles in Activated Macrophages
Membrane Ruffles Capture C3bi-opsonized Particles in Activated Macrophages
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DOI：
10.1091/mbc.e08-02-0223
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发表时间：
2008-11-01
影响因子：
3.3
通讯作者：
Harrison, Rene E.
中科院分区：
文献类型：
--
作者：
Patel, Prerna C.;Harrison, Rene E.
吞噬细胞生物学中一个普遍的观点是，Fc-Gamma R介导的吞噬作用利用膜伪足，而Mac-1介导的吞噬作用不涉及复杂的质膜延伸。在这里，我们报告了激活的巨噬细胞中的动态膜褶皱促进了C3双向调理颗粒的结合。我们认为这些褶皱是PMA和内毒素刺激的巨噬细胞巨噬细胞吞噬机制的组成部分。高亲和力的Mac-1和整合素调节蛋白talin在膜皱纹中的丰富促进了C3双颗粒的捕获。膜褶皱形成和C3双颗粒结合是细胞骨架依赖的事件，对F-肌动蛋白和微管(MTS)有很强的需求。MT破坏可钝化褶皱的形成以及PMA和内毒素诱导的表面Mac-1表达上调。此外，MT运动蛋白参与褶皱的形成，这意味着在Mac-1介导的吞噬过程中，需要将细胞内膜输送到活性膜区。我们使用TIRF成像观察到Rab11阳性囊泡与MT加端结合蛋白CLIP-170在颗粒黏附部位的共定位。Rab11与内小体循环动力学有关，突变的Rab11表达抑制了膜褶皱的形成和C3bi-SRBC与巨噬细胞的黏附。总而言之，这些发现代表了在Mac-1介导的吞噬过程中C3双颗粒结合的一种新的膜褶皱“捕获”机制。重要的是，这项工作还证明了整合素激活、巨噬细胞吞噬和巨噬细胞吞噬之间的强大功能联系。
A widespread belief in phagocyte biology is that Fc gamma R-mediated phagocytosis utilizes membrane pseudopods, whereas Mac-1-mediated phagocytosis does not involve elaborate plasma membrane extensions. Here we report that dynamic membrane ruffles in activated macrophages promote binding of C3bi-opsonized particles. We identify these ruffles as components of the macropinocytosis machinery in both PMA- and LPS-stimulated macrophages. C3bi-particle capture is facilitated by enrichment of high-affinity Mac-1 and the integrin-regulating protein talin in membrane ruffles. Membrane ruffle formation and C3bi-particle binding are cytoskeleton dependent events, having a strong requirement for F-actin and microtubules (MTs). MT disruption blunts ruffle formation and PMA- and LPS-induced up-regulation of surface Mac-1 expression. Furthermore, the MT motor, kinesin participates in ruffle formation implicating a requirement for intracellular membrane delivery to active membrane regions during Mac-1-mediated phagocytosis. We observed colocalization of Rab11-positive vesicles with CLIP-170, a MT plus-end binding protein, at sites of particle adherence using TIRF imaging. Rab11 has been implicated in recycling endosome dynamics and mutant Rab11 expression inhibits both membrane ruffle formation and C3bi-sRBC adherence to macrophages. Collectively these findings represent a novel membrane ruffle "capture" mechanism for C3bi-particle binding during Mac-1-mediated phagocytosis. Importantly, this work also demonstrates a strong functional link between integrin activation, macropinocytosis and phagocytosis in macrophages.