Analysis of SM22 at Enteropathogenic Escherichia coli Induced Pedestals

Abstract

Disease caused by enteropathogenic Escherichia coli (EPEC) is initiated when these extracellular bacteria attach onto host epithelial cells and secrete disease‐causing proteins to control the host cell machinery. Morphological actin‐rich structures, called pedestals, are formed within the host cells at sites of bacterial attachment. These structures are needed for disease to occur and are known to confer motility to the bacteria, enabling the microbes to “surf” atop the infected cells. SM22 is an actin‐associated protein that stabilizes cellular actin filament bundles. To further characterize the protein make‐up of pedestals and understand the functions of those proteins in the infectious process, we hypothesized that SM22 would be present at EPEC pedestals and would play a crucial role in forming or stabilizing these actin‐rich structures. To test this hypothesis, we immunolocalized SM22 in EPEC‐infected HeLa cells and found that SM22 localized along the entire length of the pedestals. To determine the functional role of SM22, we knocked‐down protein levels of SM22 using small interfering RNA. On cells with reduced or undetectable levels of SM22, significantly less pedestals were observed. Our data demonstrates that SM22 contributes to the formation or stability of EPEC‐induced pedestals and provides a novel target for the development of future therapeuticsThis study was funded through NSERC.