Swiprosin-1/EFhd2 Controls B Cell Receptor Signaling through the Assembly of the B Cell Receptor, Syk, and Phospholipase C γ2 in Membrane Rafts
Swiprosin-1/EFhd2 Controls B Cell Receptor Signaling through the Assembly of the B Cell Receptor, Syk, and Phospholipase C γ2 in Membrane Rafts
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DOI：
10.4049/jimmunol.0903642
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发表时间：
2010-04-01
影响因子：
4.4
通讯作者：
Mielenz, Dirk
中科院分区：
文献类型：
--
作者：
Kroczek, Carmen;Lang, Christiane;Mielenz, Dirk
BCR在膜筏中的区隔对于其信号传递能力是重要的。Swiprosin-1/EFhd2(Swip-1)是我们在膜筏中发现的具有预测的Src同源3(SH3)结合位点的EF-手和卷曲卷曲的接头蛋白。我们以前已经证明SWIP-1放大了BCR诱导的细胞凋亡；然而，这种放大的机制尚不清楚。为了解决这个问题，我们过表达了Swip-1，发现Swip-1放大了BCR诱导的WEH1231、B62.1和Bal17细胞的钙通量。相反，在SWIP-1沉默的WEH1231细胞中，BCR诱导的钙离子通量明显减弱，这是由于细胞内钙动员减少所致。Swip-1沉默的WEH1231细胞中Swip-1表达的互补可恢复BCR诱导的钙离子流动，增强脾酪氨酸激酶(Syk)酪氨酸磷酸化和活性，以及SLP65/BLNK/BASH和磷脂酶C-Gamma 2(PLC-Gamma 2)酪氨酸磷酸化。此外，Swip-1诱导BCR本身、Syk和PLC Gamma 2与膜筏的本构关系。同时，Swip-1稳定了BCR与酪氨酸磷酸化蛋白的结合，特别是Syk和PLC Gamma 2，并增强了Syk和PLC Gamma 2与Lyn的本构相互作用。有趣的是，Swip-1与Src激酶Lyn和FGR的rSH3结构域以及PLC Gamma的rSH3结构域结合。Swip-1中预测的SH3结合区的缺失减少了它以及Syk和PLC Gamma 2与膜筏的结合，减少了它与PLC Gamma的SH3结构域的相互作用，并降低了BCR诱导的钙离子通量。因此，SWIP-1提供了一种膜支架，这是依赖Syk、SLP-65和PLC Gamma 2的BCR诱导的钙离子通量所必需的。《免疫学杂志》，2010,184：3665-3676。
Compartmentalization of the BCR in membrane rafts is important for its signaling capacity. Swiprosin-1/EFhd2 (Swip-1) is an EF-hand and coiled-coil-containing adaptor protein with predicted Src homology 3 (SH3) binding sites that we identified in membrane rafts. We showed previously that Swip-1 amplifies BCR-induced apoptosis; however, the mechanism of this amplification was unknown. To address this question, we overexpressed Swip-1 and found that Swip-1 amplified the BCR-induced calcium flux in WEH1231, B62.1, and Bal17 cells. Conversely, the BCR-elicited calcium flux was strongly attenuated in Swip-1-silenced WEH1231 cells, and this was due to a decreased calcium mobilization from intracellular stores. Complementation of Swip-1 expression in Swip-1-silenced WEH1231 cells restored the BCR-induced calcium flux and enhanced spleen tyrosine kinase (Syk) tyrosine phosphorylation and activity as well as SLP65/BLNK/BASH and phospholipase C gamma 2 (PLC gamma 2) tyrosine phosphorylation. Furthermore, Swip-1 induced the constitutive association of the BCR itself, Syk, and PLC gamma 2 with membrane rafts. Concomitantly, Swip-1 stabilized the association of BCR with tyrosine-phosphorylated proteins, specifically Syk and PLC gamma 2, and enhanced the constitutive interaction of Syk and PLC gamma 2 with Lyn. Interestingly, Swip-1 bound to the rSH3 domains of the Src kinases Lyn and Fgr, as well as to that of PLC gamma. Deletion of the predicted SH3-binding region in Swip-1 diminished its association and that of Syk and PLC gamma 2 with membrane rafts, reduced its interaction with the SH3 domain of PLC gamma, and diminished the BCR-induced calcium flux. Hence, Swip-1 provides a membrane scaffold that is required for the Syk-, SLP-65-, and PLC gamma 2-dependent BCR-induced calcium flux. The Journal of Immunology, 2010, 184: 3665-3676.