Rab35 regulates phagosome formation through recruitment of ACAP2 in macrophages during FcγR-mediated phagocytosis
Rab35 regulates phagosome formation through recruitment of ACAP2 in macrophages during FcγR-mediated phagocytosis
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DOI：
10.1242/jcs.083881
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发表时间：
2011-11-01
影响因子：
4
通讯作者：
Araki, Nobukazu
中科院分区：
文献类型：
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作者：
Egami, Youhei;Fukuda, Mitsunori;Araki, Nobukazu
吞噬体形成和随后的成熟是涉及肌动蛋白细胞骨架重塑和膜运输的复杂事件序列。在这里，我们证明Ras相关蛋白Rab 35参与了Fc γ R介导的巨噬细胞吞噬作用的早期阶段。活细胞图像分析显示Rab 35明显集中在IgG调理红细胞（IgG-Es）结合的膜上。通过RNA干扰（RNAi）沉默Rab 35或表达GDP或GTP锁定的Rab 35突变体显著降低IgG-Es的吞噬率。肌动蛋白介导的伪足延伸形成吞噬杯被干扰Rab 35沉默或GDP-Rab 35的表达，虽然初始肌动蛋白组装在IgG-E结合位点不受抑制。此外，GTP-Rab 35依赖性招募ACAP 2，一种ARF 6 GTP酶激活蛋白，在吞噬杯形成。同时，过表达ACAP 2沿着GTP锁定的Rab 35显示出对吞噬作用的协同抑制作用。Rab 35可能通过招募ACAP 2来调节肌动蛋白依赖性吞噬体的形成，ACAP 2可能通过ARF 6控制肌动蛋白重塑和膜交通。
Phagosome formation and subsequent maturation are complex sequences of events that involve actin cytoskeleton remodeling and membrane trafficking. Here, we demonstrate that the Ras-related protein Rab35 is involved in the early stage of Fc gamma R-mediated phagocytosis in macrophages. Live-cell image analysis revealed that Rab35 was markedly concentrated at the membrane where IgG-opsonized erythrocytes (IgG-Es) are bound. Rab35 silencing by RNA interference (RNAi) or the expression of GDP- or GTP-locked Rab35 mutant drastically reduced the rate of phagocytosis of IgG-Es. Actin-mediated pseudopod extension to form phagocytic cups was disturbed by the Rab35 silencing or the expression of GDP-Rab35, although initial actin assembly at the IgG-E binding sites was not inhibited. Furthermore, GTP-Rab35-dependent recruitment of ACAP2, an ARF6 GTPase-activating protein, was shown in the phagocytic cup formation. Concomitantly, overexpression of ACAP2 along with GTP-locked Rab35 showed a synergistic inhibitory effect on phagocytosis. It is likely that Rab35 regulates actin-dependent phagosome formation by recruiting ACAP2, which might control actin remodeling and membrane traffic through ARF6.