Multiple roles of filopodial dynamics in particle capture and phagocytosis and phenotypes of Cdc42 and Myo10 deletion
Multiple roles of filopodial dynamics in particle capture and phagocytosis and phenotypes of Cdc42 and Myo10 deletion
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DOI：
10.1074/jbc.m116.766923
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发表时间：
2017-04-28
影响因子：
4.8
通讯作者：
Hanley, Peter J.
中科院分区：
文献类型：
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作者：
Horsthemke, Markus;Bachg, Anne C.;Hanley, Peter J.
巨噬细胞丝状突起是指状膜突起，100多年前首次与吞噬作用有关，但对这些依赖肌动蛋白的结构在颗粒清除中的作用仍知之甚少。使用旋转圆盘共聚焦显微镜对驻留在小鼠的Lifeact-EGFP巨噬细胞中的丝足动态进行成像，我们发现丝足或丝足样结构通过多种方式支持病原体清除。丝状孢子通过以下方式支持细菌(大肠杆菌)颗粒的吞噬吸收：(I)沿细丝轴轴向细胞体冲浪，这是最常见的捕获方式；(Ii)通过尖端捕获，然后回缩；(Iii)冲浪和回缩的组合；或(Iv)扫荡动作。此外，丝状孢子通过以下方式支持酵母多糖(酿酒酵母)颗粒的摄取：(I)提供固定，(Ii)在顶端捕获和丝状伪足引导的肌动蛋白顺行流动，形成吞噬杯，以及(Iii)新突起的快速生长。为了探索丝状伪足诱导的cdc42的作用，我们产生了髓系限制性的cdc42基因敲除小鼠。缺乏CdC42的巨噬细胞表现出快速的吞噬杯状动力学，但减少了颗粒清除，这可以用这些细胞显著的圆整形态来解释。缺少Myo10的巨噬细胞被认为作用于CDC42的下游，具有正常的形态、运动性和吞噬杯形成，但显示明显减少的丝足形成。总之，活细胞成像揭示了巨噬细胞丝状足在颗粒捕获和吞噬中的多种机制。CDC42对丝状孢子或吞噬细胞杯的形成不是关键的，但在驱动巨噬细胞片脂扩散方面起关键作用。
Macrophage filopodia, finger-like membrane protrusions, were first implicated in phagocytosis more than 100 years ago, but little is still known about the involvement of these actin-dependent structures in particle clearance. Using spinning disk confocal microscopy to image filopodial dynamics in mouse resident Lifeact-EGFP macrophages, we show that filopodia, or filopodia-like structures, support pathogen clearance by multiple means. Filopodia supported the phagocytic uptake of bacterial (Escherichia coli) particles by (i) capturing along the filopodial shaft and surfing toward the cell body, the most common mode of capture; (ii) capturing via the tip followed by retraction; (iii) combinations of surfing and retraction; or (iv) sweeping actions. In addition, filopodia supported the uptake of zymosan (Saccharomyces cerevisiae) particles by (i) providing fixation, (ii) capturing at the tip and filopodia-guided actin anterograde flow with phagocytic cup formation, and (iii) the rapid growth of new protrusions. To explore the role of filopodia-inducing Cdc42, we generated myeloid-restricted Cdc42 knock-out mice. Cdc42-deficient macrophages exhibited rapid phagocytic cup kinetics, but reduced particle clearance, which could be explained by the marked rounded-up morphology of these cells. Macrophages lacking Myo10, thought to act downstream of Cdc42, had normal morphology, motility, and phagocytic cup formation, but displayed markedly reduced filopodia formation. In conclusion, live-cell imaging revealed multiple mechanisms involving macrophage filopodia in particle capture and engulfment. Cdc42 is not critical for filopodia or phagocytic cup formation, but plays a key role in driving macrophage lamellipodial spreading.