Ca(2+)-independent F-actin assembly and disassembly during Fc receptor-mediated phagocytosis in mouse macrophages.
Ca(2+)-independent F-actin assembly and disassembly during Fc receptor-mediated phagocytosis in mouse macrophages.
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DOI：
10.1083/jcb.113.4.757
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发表时间：
1991-05
期刊：
影响因子：
--
通讯作者：
Silverstein SC
中科院分区：
文献类型：
--
作者：
Greenberg S;el Khoury J;di Virgilio F;Kaplan EM;Silverstein SC
假定巨噬细胞吞噬IgG包被的颗粒涉及基于肌动蛋白的细胞骨架，因为F-肌动蛋白在形成吞噬体下方积聚，并且颗粒吞噬被细胞松弛素（抑制肌动蛋白丝组装的药物）阻断。然而，目前尚不清楚Fc受体连接是否会影响IgG包被颗粒吞噬过程中F-肌动蛋白组装的速率或程度。为了研究这个问题，我们已经使用了定量荧光分光光度法来检查F-肌动蛋白的动态过程中的IgG包被的红细胞的吞噬炎性小鼠巨噬细胞的同步波。我们观察到的颗粒吞噬过程中的巨噬细胞F-肌动蛋白含量的双相上升，在1和5分钟后开始吞噬作用的最大值。F-肌动蛋白下降到静息水平的30分钟，由该时间粒子吞噬完成。巨噬细胞F-肌动蛋白的这些定量增加反映在F-肌动蛋白分布的局部变化中。先前的工作表明，被巨噬细胞吞噬的IgG包被的颗粒的数量不受缓冲细胞外钙或将胞质游离钙浓度（[Ca 2 +]i）夹持至非常低的水平的影响（Di P.，F.，B。C.迈耶，S。Greenberg和S. C.西尔弗斯坦1988. 106：657-666）。为了确定巨噬细胞中的[Ca 2 +]i钳制是否影响颗粒吞噬的速率，或吞噬过程中F-肌动蛋白的组装或分解，我们在巨噬细胞中检测了这些参数，所述巨噬细胞的[Ca 2 +]i已经用fura 2/AM和EGTA的乙酰氧基甲基酯钳制至约小于3 nM。我们发现，在Ca（2+）-充盈和Ca（2+）-耗尽的巨噬细胞中，吞噬的初始速率以及组装和分解的F-肌动蛋白的量是相似的。我们的结论是，Fc受体介导的小鼠巨噬细胞的吞噬作用是伴随着一个有序的序列的组装和拆卸的F-肌动蛋白是不敏感的[Ca 2 +]i。
Phagocytosis of IgG-coated particles by macrophages is presumed to involve the actin-based cytoskeleton since F-actin accumulates beneath forming phagosomes, and particle engulfment is blocked by cytochalasins, drugs that inhibit actin filament assembly. However, it is unknown whether Fc receptor ligation affects the rate or extent of F- actin assembly during phagocytosis of IgG-coated particles. To examine this question we have used a quantitative spectrofluorometric method to examine F-actin dynamics during a synchronous wave of phagocytosis of IgG-coated red blood cells by inflammatory mouse macrophages. We observed a biphasic rise in macrophage F-actin content during particle engulfment, with maxima at 1 and 5 min after the initiation of phagocytosis. F-actin declined to resting levels by 30 min, by which time particle engulfment was completed. These quantitative increases in macrophage F-actin were reflected in localized changes in F-actin distribution. Previous work showed that the number of IgG-coated particles engulfed by macrophages is unaffected by buffering extracellular calcium or by clamping cytosolic free calcium concentration ([Ca2+]i) to very low levels (Di Virgilio, F., B. C. Meyer, S. Greenberg, and S. C. Silverstein. 1988. J. Cell Biol. 106: 657-666). To determine whether clamping [Ca2+]i in macrophages affects the rate of particle engulfment, or the assembly or disassembly of F- actin during phagocytosis, we examined these parameters in macrophages whose [Ca2+]i had been clamped to approximately less than 3 nM with fura 2/AM and acetoxymethyl ester of EGTA. We found that the initial rate of phagocytosis, and the quantities of F-actin assembled and disassembled were similar in Ca(2+)-replete and Ca(2+)-depleted macrophages. We conclude that Fc receptor-mediated phagocytosis in mouse macrophages is accompanied by an ordered sequence of assembly and disassembly of F-actin that is insensitive to [Ca2+]i.
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