EPEC pedestal on an intestinal cell

After attaching loosely to intestinal cells, E. coli induces an actin-rich ‘pedestal’ upon which they attach very strongly.

Pedestal formation is induced by bacterial proteins that are injected into the intestinal cell

Effacement of intestinal microvilli

 During the early stages of  infection, E. coli rapidly removes  microvilli on the surface of small intestinal cells

The microvilli (grey) are lost both underneath and around the bacteria. My work has shown that this is induced by at least 4 bacterial proteins (see paper)

Effacement of intestinal microvilli

E.coli on the surface of Caco-2 cells causing a increasing zone of peripheral effacement around the dividing bacteria

Localised loss of microvilli

One of the first events following attachemnt to inestinal cells is the loss of microvilli beneath E. coli - resulting in the bacteria sinking down into the microvilli brush border

The activities of EPEC’s effector Proteins

E. coli transfers many different proteins into its host cell. One of these proteins (shown in green) target the host cell’s mitochondria - an organelle that  provides energy for the cell

Bacteria are shown in blue (DAPI) and the red staining (phalloidin) shows actin-based pedestals 

E. coli’s effector proteins are multifunctional

Inside the host cell, the different E.coli proteins target multiple sites and signaling pathways. Here, two effector proteins are shown in red and green with the yellow colour indicating where these two  proteins  target similar sites

Bacteria are shown in blue

Filopodia formation on the surface of intestinal cells

EPEC induces the transient formation of actin protrusions called filopodia (shown in Red) on the surface of intestinal cells

Filopodia formation is induced by the EPEC effector protein Map (see paper)

Bacteria are shown in blue

                  Uninfected                             EPEC-infected        

EPEC destroys tight junctions between intestinal cells

Intestinal cells make tight junctions between one another - forming a barrier to the leakage of water from our body into our gut lumen

By breaking these junctions, the seal is broken and this is one mechanism that may contribute to diarrhoea caused by EPEC (see paper)