Streptococcus pyogenes M49 plasminogen/plasmin binding facilitates keratinocyte invasion via integrin-integrin-linked kinase (ILK) pathways and protects from macrophage killing

J Biol Chem. 2011 Jun 17;286(24):21612-22. doi: 10.1074/jbc.M110.202671. Epub 2011 Apr 26.

Abstract

The entry into epithelial cells and the prevention of primary immune responses are a prerequisite for a successful colonization and subsequent infection of the human host by Streptococcus pyogenes (group A streptococci, GAS). Here, we demonstrate that interaction of GAS with plasminogen promotes an integrin-mediated internalization of the bacteria into keratinocytes, which is independent from the serine protease activity of potentially generated plasmin. α(1)β(1)- and α(5)β(1)-integrins were identified as the major keratinocyte receptors involved in this process. Inhibition of integrin-linked kinase (ILK) expression by siRNA silencing or blocking of PI3K and Akt with specific inhibitors, reduced the GAS M49-plasminogen/plasmin-mediated invasion of keratinocytes. In addition, blocking of actin polymerization significantly reduced GAS internalization into keratinocytes. Altogether, these results provide a first model of plasminogen-mediated GAS invasion into keratinocytes. Furthermore, we demonstrate that plasminogen binding protects the bacteria against macrophage killing.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacteriocins / metabolism*
  • Cell Adhesion
  • Cell Line, Tumor
  • Fibrinolysin / metabolism
  • Humans
  • Integrin alpha1beta1 / metabolism
  • Integrin alpha5beta1 / metabolism
  • Integrins / metabolism*
  • Keratinocytes / metabolism*
  • Keratinocytes / microbiology
  • Macrophages / microbiology
  • Models, Biological
  • Models, Genetic
  • Peptides / metabolism*
  • Protein Binding
  • Protein Serine-Threonine Kinases / metabolism*
  • Streptococcus pyogenes / metabolism*

Substances

  • Bacteriocins
  • Integrin alpha1beta1
  • Integrin alpha5beta1
  • Integrins
  • Peptides
  • streptococcin A M49 protein, Streptococcus
  • integrin-linked kinase
  • Protein Serine-Threonine Kinases
  • Fibrinolysin