Staphylococcus aureus protein A activates TACE through EGFR‐dependent signaling

MI Gómez, MO Seaghdha, AS Prince - The EMBO journal, 2007 - embopress.org
The EMBO journal, 2007embopress.org
Among the many adhesins and toxins expressed by Staphylococcus aureus, protein A is an
exceptionally complex virulence factor, known to interact with multiple eukaryotic targets,
particularly those with immunological functions. Protein A acts as a ligand that can mimic
TNF‐α to activate TNFR1 and subsequent proinflammatory signaling. It also stimulates the
cleavage of TNFR1 from the surface of epithelial cells and macrophages, which serves to
limit TNF‐α signaling. We characterized the signaling pathway responsible for TNFR1 …
Among the many adhesins and toxins expressed by Staphylococcus aureus, protein A is an exceptionally complex virulence factor, known to interact with multiple eukaryotic targets, particularly those with immunological functions. Protein A acts as a ligand that can mimic TNF‐α to activate TNFR1 and subsequent proinflammatory signaling. It also stimulates the cleavage of TNFR1 from the surface of epithelial cells and macrophages, which serves to limit TNF‐α signaling. We characterized the signaling pathway responsible for TNFR1 shedding and identified protein A mutants which could activate TNFR1‐dependent signaling, but were unable to activate TACE, the TNFR1 sheddase. Activation of TACE was dependent upon a discrete interaction between the previously defined IgG‐binding domain of protein A and the epidermal growth factor receptor (EGFR), which in turn induced TACE phosphorylation through a c‐Src‐erk1/2‐mediated cascade. This novel interaction was independent of the autocrine activation of EGFR and protein A‐induced TGF‐α was neither required nor sufficient to activate TNFR1 shedding. Thus, staphylococci exploit the ubiquitous and multifunctional EGFR to regulate the availability of TNFR1 on mucosal and immune cells.
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