CIN85 Modulates the Down-regulation of FcγRIIa Expression and Function by c-Cbl in a PKC-dependent Manner in Human Neutrophils
CIN85 Modulates the Down-regulation of FcγRIIa Expression and Function by c-Cbl in a PKC-dependent Manner in Human Neutrophils
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DOI：
10.1074/jbc.m110.213660
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发表时间：
2011-04-29
影响因子：
4.8
通讯作者：
Naccache, Paul H.
中科院分区：
文献类型：
--
作者：
Marois, Louis;Vaillancourt, Myriam;Naccache, Paul H.
我们之前描述了一种非经典机制，一旦被免疫复合物或调理病原体参与，就会阻止人类中性粒细胞中的 Fc gamma RIIa 信号传导。 Fc gamma RIIa 的参与导致其被泛素连接酶 c-Cbl 泛素化并被蛋白酶体降解。在此，我们进一步研究了调节这一新途径的一些事件。在其他系统中，接头蛋白 CIN85 被描述为参与 c-Cbl 依赖性途径的调节。我们发现 CIN85 在人中性粒细胞中表达，并且在受体交联后，它像 c-Cbl 一样从胞质溶胶易位到质膜。 CIN85 也被招募到高密度耐去污剂膜级分的相同亚组中，其中受刺激的 Fc γ RIIa 与 c-Cbl 分开。这些微结构域的完整性对于 Fc gamma RIIa 降解过程至关重要，因为胆固醇消耗剂甲基-β-环糊精会抑制这一事件。在二丁酰环 AMP 分化的 PLB 985 细胞中通过 siRNA 沉默 CIN85 的表达可防止 Fc gamma RIIa 降解并增加 IgG 介导的吞噬作用。共聚焦显微镜显示，CIN85 的存在对于胞吞过程中 Fc gamma RIIa 的正确分选至关重要。我们还提供了直接证据表明 CIN85 是丝氨酸/苏氨酸激酶 PKC 的底物。经典 PKC 正向调节 Fc gamma RIIa 泛素化和降解，因为这些事件被经典 PKC 抑制剂 Go6976 抑制。我们得出的结论是，c-Cbl 介导的受刺激的 Fc γ RIIa 的泛素化和降解受到接头蛋白 CIN85 以 PKC 依赖性方式正向调节，并且这些事件有助于终止 Fc γ RIIa 信号传导。
We previously described a non-classical mechanism that arrests Fc gamma RIIa signaling in human neutrophils once engaged by immune complexes or opsonized pathogens. The engagement of Fc gamma RIIa leads to its ubiquitination by the ubiquitin ligase c-Cbl and degradation by the proteasome. Herein, we further examined some of the events regulating this novel pathway. The adaptor protein CIN85 was described in other systems to be involved in the regulation of the c-Cbl-dependent pathway. We found that CIN85 is expressed in human neutrophils and that it translocates like c-Cbl from the cytosol to the plasma membrane following receptor cross-linking. CIN85 was also recruited to the same subset of high density detergent-resistant membrane fractions in which stimulated Fc gamma RIIa partitioned with c-Cbl. The integrity of these microdomains is essential to the Fc gamma RIIa degradation process because the cholesterol-depleting agent methyl-beta-cyclodextrin inhibits this event. Silencing the expression of CIN85 by siRNA in dibutyryl cyclic AMP-differentiated PLB 985 cells prevented Fc gamma RIIa degradation and increased IgG-mediated phagocytosis. Confocal microscopy revealed that the presence of CIN85 is essential to the proper sorting of Fc gamma RIIa during endocytosis. We also provide direct evidence that CIN85 is a substrate of serine/threonine kinase PKCs. Classical PKCs positively regulate Fc gamma RIIa ubiquitination and degradation because these events were inhibited by Go6976, a classical PKC inhibitor. We conclude that the ubiquitination and degradation of stimulated Fc gamma RIIa mediated by c-Cbl are positively regulated by the adaptor protein CIN85 in a PKC-dependent manner and that these events contribute to the termination of Fc gamma RIIa signaling.