Wiedemann A, Linder S, Grassl G, Albert M, Autenrieth I, Aepfelbacher M
Max von Pettenkofer-Institut für Medizinische Mikrobiologie, Pettenkoferstrasse 9a, Ludwig-Maximilians-Universität, 80336 München, Germany.
Cell Microbiol. 2001 Oct;3(10):693-702. doi: 10.1046/j.1462-5822.2001.00149.x.
The Yersinia outer surface protein invasin binds to beta1 integrins on target cells and has been shown to trigger phagocytic uptake by macrophages. Here, we investigated the role of the actin regulator Wiskott-Aldrich syndrome protein (WASp), its effector the Arp2/3 complex and the Rho-GTPases CDC42Hs, Rac and Rho in invasin/beta1 integrin-triggered phagocytosis. During uptake of invasin-coated latex beads, the alpha5beta1 integrin, WASp and the Arp2/3 complex were recruited to the developing actin-rich phagocytic cups in primary human macrophages. Blockage of beta1 integrins by specific antibodies, inhibition of Arp2/3 function by microinjection of inhibitors or the use of WASp knockout macrophages inhibited phagocytic cup formation and uptake. Furthermore, microinjection of the dominant negative GTPase mutants N17CDC42Hs, N17Rac or the Rho-specific inhibitor C3-transferase into macrophages greatly attenuated invasin-induced formation of cups. These data suggest that during invasin-triggered phagocytosis beta1 integrins activate actin polymerization via CDC42Hs, its effector WASp and the Arp2/3 complex. The contribution of Rac and Rho to phagocytic cup formation also suggests a complex interplay between different Rho GTPases during phagocytosis of pathogens.
耶尔森氏菌外表面蛋白侵袭素可与靶细胞上的β1整合素结合，并且已证实它能触发巨噬细胞的吞噬摄取。在此，我们研究了肌动蛋白调节剂威斯科特-奥尔德里奇综合征蛋白（WASp）、其效应蛋白Arp2/3复合物以及Rho-GTP酶CDC42Hs、Rac和Rho在侵袭素/β1整合素触发的吞噬作用中的作用。在摄取包被有侵袭素的乳胶珠的过程中，α5β1整合素、WASp和Arp2/3复合物被募集到原代人巨噬细胞中正在形成的富含肌动蛋白的吞噬杯处。用特异性抗体阻断β1整合素、通过显微注射抑制剂抑制Arp2/3功能或使用WASp基因敲除巨噬细胞均会抑制吞噬杯的形成和摄取。此外，向巨噬细胞中显微注射显性负性GTP酶突变体N17CDC42Hs、N17Rac或Rho特异性抑制剂C3转移酶会大大减弱侵袭素诱导的杯状结构形成。这些数据表明，在侵袭素触发的吞噬作用过程中，β1整合素通过CDC42Hs、其效应蛋白WASp和Arp2/3复合物激活肌动蛋白聚合。Rac和Rho对吞噬杯形成的作用也表明，在病原体吞噬过程中，不同的Rho GTP酶之间存在复杂的相互作用。
