UMR 1282 Infectiologie et Santé Publique, Institut National de la Recherche Agronomique (INRA), F-37380 Nouzilly, France.
J Biol Chem. 2012 Sep 7;287(37):31148-54. doi: 10.1074/jbc.M112.392134. Epub 2012 Jul 18.
The Salmonella outer membrane protein Rck mediates a Zipper entry mechanism controlled by tyrosine phosphorylation and class I phosphatidylinositol 3-kinase (PI 3-kinase). However, the underlying mechanism leading to this signaling cascade remains unclear. The present study showed that using Rck-coated beads or Rck-overexpressing Escherichia coli, Rck-mediated actin polymerization and invasion were blocked by PP2, a Src family tyrosine kinase inhibitor. In addition, phosphorylation of Src family kinases significantly increased after stimulation with Rck. The specific contribution of c-Src, one member of the Src family kinases, was demonstrated using c-Src-deficient fibroblasts or c-Src siRNA transfected epithelial cells. We also observed that Rck-mediated internalization led to the formation of a complex between c-Src and at least one tyrosine-phosphorylated protein. Furthermore, our results revealed that the c-Src signal molecule was upstream of PI 3-kinase during the Rck-mediated signaling pathway as Rck-mediated PI 3-kinase activation was blocked by PP2, and PI 3-kinase inhibitor had no effect on the Src phosphorylation. These results demonstrate the involvement of c-Src upstream of the PI 3-kinase in the Zipper entry process mediated by Rck.
沙门氏菌外膜蛋白 Rck 通过酪氨酸磷酸化和 I 类磷酸肌醇 3-激酶（PI 3-激酶）介导拉链进入机制。然而，导致这种信号级联的潜在机制仍不清楚。本研究表明，使用 Rck 包被珠或 Rck 过表达大肠杆菌，Src 家族酪氨酸激酶抑制剂 PP2 阻断了 Rck 介导的肌动蛋白聚合和侵袭。此外，Rck 刺激后 Src 家族激酶的磷酸化显著增加。使用 c-Src 缺陷成纤维细胞或转染 c-Src siRNA 的上皮细胞证明了 Src 家族激酶之一 c-Src 的特定作用。我们还观察到，Rck 介导的内化导致 c-Src 和至少一种酪氨酸磷酸化蛋白之间形成复合物。此外，我们的结果表明，在 Rck 介导的信号通路中，c-Src 信号分子位于 PI 3-激酶的上游，因为 Rck 介导的 PI 3-激酶激活被 PP2 阻断，而 PI 3-激酶抑制剂对 Src 磷酸化没有影响。这些结果表明，c-Src 在 Rck 介导的拉链进入过程中位于 PI 3-激酶的上游。
