Pseudomonas signal molecule 3-oxo-c12-homoserine lactone interferes with binding of rosiglitazone to human PPARγ
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Peroxisome proliferator activated receptor (PPAR?) has been suggested as a target for anti-inflammatory therapy in chronic lung disease, including infection with Pseudomonas aeruginosa. However, the P. aeruginosa signal molecule N-(3-oxo-dodecanoyl)-l-homoserine lactone (3-oxo-C12-HSL) has been reported to inhibit function of PPARs in mammalian cells. This suggests that binding of 3-oxo-C12-HSL to PPARs could increase inflammation during P. aeruginosa infection, particularly if it could compete for binding with other PPAR ligands. We investigated the ability of 3-oxo-C12-HSL to bind to a PPAR? ligand binding domain (LBD) construct, and to compete for binding with the highly active synthetic PPAR? agonist rosiglitazone. We demonstrate that 3-oxo-C12-HSL binds effectively to the PPAR? ligand binding domain, and that concentrations of 3-oxo-C12-HSL as low as 1 nM can effectively interfere with the binding of rosiglitazone to the PPAR? ligand binding domain. Because 3-oxo-C12 HSL has been demonstrated in lungs during P. aeruginosa infection, blockade of PPAR?-dependent signaling by 3-oxo-C12-HSL produced by the infecting P. aeruginosa could exacerbate infection-associated inflammation, and potentially impair the action of PPAR-activating therapy. Thus the proposed use of PPAR? agonists as anti-inflammatory therapy in lung P. aeruginosa infection may depend on their ability to counteract the effects of 3-oxo-C12-HSL.
Microbes and Infection