Fc gamma RII-mediated adhesion and phagocytosis induce L-plastin phosphorylation in human neutrophils
Fc gamma RII-mediated adhesion and phagocytosis induce L-plastin phosphorylation in human neutrophils
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DOI：
10.1074/jbc.271.24.14623
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发表时间：
1996-06-14
影响因子：
4.8
通讯作者：
Brown, EJ
中科院分区：
文献类型：
--
作者：
Jones, SL;Brown, EJ
L-Plastin是白细胞和一些转化细胞中表达的钙调节的肌动蛋白成束蛋白，其响应于几种不同的白细胞活化刺激而在丝氨酸上磷酸化。粘附到免疫复合物诱导L-纤溶酶磷酸化的中性粒细胞，IgG调理颗粒的吞噬作用，但悬浮液中的不溶性免疫复合物是非常低效的激活剂L-纤溶酶磷酸化。中性粒细胞表达两种IgG Fc受体，即跨膜Fc γ RII和聚糖磷酸肌醇连接的Fc γ RIIIB。使用区分两种Fc受体的单克隆抗体证明，Fc γ RII连接在信号传导L-纤溶酶磷酸化方面比Fc γ RIIIB的占据有效100倍。细胞内钙的消耗不影响Fc γ RII活化的L-纤溶酶磷酸化，证明钙对纤溶酶功能的任何潜在调节不影响其磷酸化，与免疫复合物的粘附导致L-纤溶酶定位于足小体，因为它与肌动蛋白共定位于粘附的中性粒细胞表面上的离散的、点状的Triton X-100不溶性位点，其模式与黏着斑蛋白和α-辅肌动蛋白难以区分。尽管如此，定位于足小体对于L-纤溶酶磷酸化不是必需的，由于来自白细胞粘附缺陷患者的中性粒细胞（CD 18缺陷）和用抗-CD 18 F（ab '）a处理的中性粒细胞，其在粘附于免疫复合物时不形成podosomes，磷酸化的L-纤溶酶原蛋白正常，实际上，即使肌动蛋白细胞骨架被细胞松弛素D破坏，L-纤维蛋白原在正常情况下也会磷酸化以响应对免疫复合物的粘附。我们的结论是，有效的Fc γ RII介导的磷酸化L-纤维蛋白需要细胞粘附，但不需要IgG诱导的肌动蛋白细胞骨架重排。这些数据表明，在一个模型中，在粘附于免疫复合物的中性粒细胞中，纤溶酶磷酸化和定位于肌动蛋白细胞骨架可以作为调节L-纤溶酶功能的两种不同机制。
L-Plastin is a calcium-regulated actin bundling protein expressed in leukocytes and some transformed cells, which is phosphorylated on serine in response to several different leukocyte-activating stimuli. Adhesion to immune complexes induced L-plastin phosphorylation in neutrophils, as did phagocytosis of IgG-opsonized particles, but insoluble immune complexes in suspension were very inefficient activators of L-plastin phosphorylation. Neutrophils express two IgG Fc receptors, the transmembrane Fc gamma RII and the glycan phosphoinositol-linked Fc gamma RIIIB. Use of monoclonal antibodies that distinguished the two Fc receptors demonstrated that Fc gamma RII ligation was 100-fold more potent at signaling L-plastin phosphorylation than occupancy of Fc gamma RIIIB, Depletion of intracellular calcium did not affect Fc gamma RII-activated L-plastin phosphorylation, demonstrating that any potential regulation of plastin function by calcium did not affect its phosphorylation, Adhesion to immune complexes caused L-plastin to localize to podosomes, since it colocalized with actin to discrete, punctate Triton X-100-insoluble sites on the adherent neutrophil surface in a pattern indistinguishable from vinculin and alpha-actinin, Nonetheless, localization to podosomes was not required for L-plastin phosphorylation, since both neutrophils from a patient with leukocyte adhesion deficiency (CD18 deficiency) and neutrophils treated with anti-CD18 F(ab')a, which do not form podosomes upon adhesion to immune complexes, phosphorylated L-plastin normally, Indeed, L-plastin was normally phosphorylated in response to adhesion to immune complexes even when the actin cytoskeleton was disrupted with cytochalasin D. We conclude that efficient Fc gamma RII-mediated phosphorylation of L-plastin requires cell adhesion but does not require IgG-induced rearrangements of the actin cytoskeleton. These data suggest a model in which plastin phosphorylation and localization to the actin cytoskeleton can act as two distinct mechanisms regulating L-plastin functions in neutrophils adherent to immune complexes.