Involvement of c-Src tyrosine kinase upstream of class I phosphatidylinositol (PI) 3-kinases in Salmonella Enteritidis Rck protein-mediated invasion

J Biol Chem. 2012 Sep 7;287(37):31148-54. doi: 10.1074/jbc.M112.392134. Epub 2012 Jul 18.

Abstract

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.

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • CSK Tyrosine-Protein Kinase
  • Cell Line
  • Enzyme Activation / genetics
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Humans
  • Multiprotein Complexes / genetics
  • Multiprotein Complexes / metabolism*
  • Phosphatidylinositol 3-Kinases / genetics
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Protein-Tyrosine Kinases / genetics
  • Protein-Tyrosine Kinases / metabolism*
  • Salmonella Infections / genetics
  • Salmonella Infections / metabolism*
  • Salmonella enteritidis / genetics
  • Salmonella enteritidis / metabolism*
  • src-Family Kinases

Substances

  • Bacterial Proteins
  • Multiprotein Complexes
  • Protein-Tyrosine Kinases
  • CSK Tyrosine-Protein Kinase
  • src-Family Kinases
  • CSK protein, human