The role of actin microfilaments in the down-regulation of the degranulation response in RBL-2H3 mast cells.
The role of actin microfilaments in the down-regulation of the degranulation response in RBL-2H3 mast cells.
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DOI：
10.4049/jimmunol.162.4.2243
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发表时间：
1999-02
影响因子：
4.4
通讯作者：
L. Frigeri;J. Apgar
中科院分区：
文献类型：
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作者：
L. Frigeri;J. Apgar
大鼠嗜碱性白血病（RBL）细胞上FcepsilonRI的交联引发信号级联反应，导致细胞脱粒和炎症介质的释放。破坏微丝的抑制剂，如latrunculin和细胞松弛素D，本身不会引起任何脱粒，但它们确实增强了FcepsilonRI介导的脱粒。剂量反应研究表明，抑制肌动蛋白聚合和增加脱粒之间有很好的相关性。在RBL细胞中，latrunculin导致丝状肌动蛋白（F-肌动蛋白）的基础水平下降，而细胞松弛素D则不会。这在高度交联并与质膜相关的F-肌动蛋白的Triton不溶性池中特别明显。浓度为500 nM的latrunculin使Triton不溶性F-肌动蛋白的基础水平降低60-70%，总F-肌动蛋白水平降低25%。Latrunculin增加银诱导的脱粒的速率和程度，而对过钒酸盐诱导的脱粒没有影响。过钒酸盐直接激活信号通路并绕过受体的交联。RBL细胞在存在拉曲库林的情况下通过Fc ε RI活化，显示出磷脂酶活性增加以及Syk的酪氨酸磷酸化增加和受体本身通过酪氨酸激酶林恩的酪氨酸磷酸化增加。这表明受体交联后最早的信号传导事件被增强。这些结果表明，肌动蛋白微丝可以相互作用，直接或间接地，与受体本身，它们可以调节信号转导过程中的受体磷酸化水平。微丝可能通过使林恩与交联受体解偶联而起作用。
Cross-linking of FcepsilonRI on rat basophilic leukemia (RBL) cells initiates a signaling cascade leading to degranulation of the cells and the release of inflammatory mediators. Inhibitors that disrupt microfilaments, such as latrunculin and cytochalasin D, do not cause any degranulation on their own, but they do enhance FcepsilonRI-mediated degranulation. Dose-response studies show a good correlation between inhibition of actin polymerization and increased degranulation. In RBL cells, latrunculin causes a decrease in basal levels of filamentous actin (F-actin), while cytochalasin D does not. This is particularly evident in the Triton-insoluble pool of F-actin which is highly cross-linked and associated with the plasma membrane. A concentration of 500 nM latrunculin decreases the basal level of Triton-insoluble F-actin by 60-70% and total F-actin levels by 25%. Latrunculin increases both the rate and extent of Ag-induced degranulation while having no effect on pervanadate-induced degranulation. Pervanadate activates the signaling pathways directly and bypasses the cross-linking of the receptor. RBL cells, activated through FcepsilonRI in the presence of latrunculin, show increased phospholipase activity as well as increased tyrosine phosphorylation of Syk and increased tyrosine phosphorylation of the receptor itself by the tyrosine kinase Lyn. This indicates that the very earliest signaling events after receptor cross-linking are enhanced. These results suggest that actin microfilaments may interact, either directly or indirectly, with the receptor itself and that they may regulate the signaling process at the level of receptor phosphorylation. Microfilaments may possibly act by uncoupling Lyn from the cross-linked receptor.