Leukocyte transmigration is modulated by chemokine-mediated PI3Kγ-dependent phosphorylation of vimentin
Leukocyte transmigration is modulated by chemokine-mediated PI3Kγ-dependent phosphorylation of vimentin
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DOI：
10.1002/eji.200838884
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发表时间：
2009-04-01
影响因子：
5.4
通讯作者：
Hirsch, Emilio
中科院分区：
文献类型：
--
作者：
Barberis, Laura;Pasquali, Christian;Hirsch, Emilio
磷脂酰肌醇3-激酶γ（PI 3 K-γ）在介导白细胞迁移至炎症部位中起重要作用。然而，由其信号传导活性触发的下游细胞质事件在很大程度上仍然不清楚。为了解决这个问题，研究了趋化因子刺激的WT或PI 3 K γ-无效巨噬细胞的酪氨酸和丝氨酸/苏氨酸磷酸化蛋白。在分析的蛋白质中，发现中间丝波形蛋白是PI 3 K-γ信号通路的下游效应物。对巨噬细胞中波形蛋白磷酸化状态的特异性分析表明，该蛋白在趋化因子刺激后酪氨酸和丝氨酸残基迅速磷酸化。在不存在PI 3 K-γ或PI 3 K-γ的激酶活性（PI 3 K-γ（KD/KD））的情况下，波形蛋白的磷酸化降低。PI 3 K-γ-无效巨噬细胞显示趋化因子驱动的波形蛋白纤维分解受损以及穿过内皮细胞的能力降低。而WT巨噬细胞;用对N-末端丝氨酸磷酸化有抗性的波形蛋白突变体感染的巨噬细胞显示出跨内皮迁移的减少，用模拟N-末端残基的丝氨酸磷酸化的波形蛋白突变体感染PI 3 K-γ-无效的巨噬细胞拯救了跨内皮迁移缺陷。这些结果将波形蛋白N-末端磷酸化和纤维重组定义为白细胞中趋化蛋白依赖性PI 3 K-γ信号传导的靶标。
Phosphoinositide 3-kinase gamma (PI3K-gamma) plays a fundamental role in mediating leukocyte migration to inflammation sites. However, the downstream cytoplasmic events triggered by its signaling activity are still largely obscure. To address this issue, tyrosine and serine/threonine phosphorylated proteins of chemokine-stimulated WT or PI3K gamma-null macrophages were investigated. Among the proteins analyzed, the intermediate filament vimentin was found as a downstream effector of the PI3K-gamma signaling pathway. Specific analysis of the phosphorylation state of vimentin in macrophages showed that this protein becomes rapidly phosphorylated in both tyrosine and serine residues upon chemokine stimulation. In the absence of PI3K-gamma or the kinase activity of PI3K-gamma (PI3K-gamma(KD/KD)), phosphorylation of vimentin was reduced. PI3K-gamma-null macrophages displayed impaired chemokine-driven vimentin fiber disassembly as well as reduced ability to transmigrate across endothelial cells. While WT macrophages; infected with a vimentin mutant resistant to N-terminal serine phosphorylation showed a reduction in transendothelial migration, infection of PI3K-gamma-null macrophages with a vimentin mutant mimicking serine phosphorylation of N-terminal residues rescued the transendothelial migration defect. These results define vimentin N-terminal phosphorylation and fiber reorganization as a target of chemoldne-dependent PI3K-gamma signaling in leukocytes.