Department of Laboratory Medicine

IQGAP1 and Salmonella Pathogenesis

Pathogenic microbes have evolved diverse strategies to invade the host, avoid the innate immune response and multiply. The invasion of human cells by pathogens is observed in food-borne illnesses caused by Salmonella, Shigella and Listeria as well as periodontal (gum) infections. Microbial invasion of host cells is largely achieved by the pathogens' usurping of host signaling pathways. A common target of pathogens is the host cell's actin cytoskeleton, which the microbes use for attachment, entry into cells, movement within and between cells and avoidance of phagocytosis.

Confocal micrograph illustrating Salmonella attaching to the actin cytoskeleton and entering cultured mouse embryonic fibroblasts (MEFs). Bacteria gain entry into the cells after & 1 minute of exposure.
Confocal micrograph illustrating Salmonella (green, arrows) attaching to the actin cytoskeleton (red staining) and entering cultured mouse embryonic fibroblasts (MEFs). Bacteria gain entry into the cells after < 1 minute of exposure (Kim, et al. Biochem J, 2011).

The actin-binding protein IQGAP1 is an established regulator of normal cytoskeletal function and may play a role in the invasion of human cells by microbial pathogens. My laboratory is presently investigating the IQGAP1-mediated mechanisms by which Salmonella subverts the actin cytoskeleton to establish infection.

Confocal micrographs illustrating the co-localization of actin (far-left panel) with the actin-binding protein IQGAP1 (left panel). Notably, IQGAP1 is recruited to the sites of Salmonella invasion into HeLa cells (right panel).The co-localization of actin, IQGAP1 and Salmonella is illustrated in the merge (far-right panel)
Confocal micrographs illustrating the co-localization of actin (blue, far-left panel) with the actin-binding protein IQGAP1 (green, left panel). Notably, IQGAP1 is recruited to the sites of Salmonella invasion into HeLa cells (red, right panel).The co-localization of actin, IQGAP1 and Salmonella is illustrated in the merge (far-right panel) (Kim, et al. Biochem J, 2011).

Schematic diagram illustrates the hijacking of the host cell's actin cytoskeleton by Salmonella, allowing microbial invasion. This process may be regulated by IQGAP1
Schematic diagram illustrates the hijacking of the host cell's actin cytoskeleton by Salmonella, allowing microbial invasion. This process may be regulated by IQGAP1 (Kim, et al. Biochem J, 2011).

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This page last updated on 06/09/2017

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