Clathrin, AP-2, and the NPXY-binding subset of alternate endocytic adaptors facilitate FimH-mediated bacterial invasion of host cells

Cell Microbiol. 2008 Dec;10(12):2553-67. doi: 10.1111/j.1462-5822.2008.01229.x. Epub 2008 Aug 25.

Abstract

The FimH adhesin, localized at the distal tips of type 1 pili, binds mannose-containing glycoprotein receptors like alpha3beta1 integrins and stimulates bacterial entry into target host cells. Strains of uropathogenic Escherichia coli (UPEC), the major cause of urinary tract infections, utilize FimH to invade bladder epithelial cells. Here we set out to define the mechanism by which UPEC enters host cells by investigating four of the major entry routes known to be exploited by invasive pathogens: caveolae, clathrin, macropinocytosis and secretory lysosomes. Using pharmacological inhibitors in combination with RNA interference against specific endocytic pathway components, mutant host cell lines and a mouse infection model system, we found that type 1 pili-dependent bacterial invasion of host cells occurs via a cholesterol- and dynamin-dependent phagocytosis-like mechanism. This process did not require caveolae or secretory lysosomes, but was modulated by calcium levels, clathrin, and cooperative input from the primary clathrin adaptor AP-2 and a subset of alternate adaptors comprised of Numb, ARH and Dab2. These alternate clathrin adaptors recognize NPXY motifs, as found within the cytosolic tail of beta1 integrin, suggesting a functional link between the engagement of integrin receptors by FimH and the clathrin-dependent uptake of type 1-piliated bacteria.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adaptor Protein Complex 2 / metabolism*
  • Adaptor Proteins, Signal Transducing / metabolism
  • Adhesins, Escherichia coli / metabolism*
  • Animals
  • Apoptosis Regulatory Proteins
  • Cell Line
  • Clathrin / metabolism*
  • Endocytosis*
  • Epithelial Cells / microbiology*
  • Escherichia coli / physiology*
  • Fimbriae Proteins / metabolism*
  • Gene Silencing
  • Humans
  • Membrane Proteins / metabolism
  • Mice
  • Nerve Tissue Proteins / metabolism
  • Tumor Suppressor Proteins
  • Urinary Tract Infections / microbiology

Substances

  • Adaptor Protein Complex 2
  • Adaptor Proteins, Signal Transducing
  • Adhesins, Escherichia coli
  • Apoptosis Regulatory Proteins
  • Clathrin
  • DAB2 protein, human
  • LDLRAP1 protein, human
  • Membrane Proteins
  • Nerve Tissue Proteins
  • NUMB protein, human
  • Tumor Suppressor Proteins
  • fimH protein, E coli
  • Fimbriae Proteins