Electrophilic fatty acids regulate matrix metalloproteinase activity and expression

Abstract

Nitro-fatty acids (NO2-FA) are electrophilic signaling mediators formed by reactions of nitric oxide and nitrite. NO2-FA exert anti-inflammatory signaling actions through post-translational protein modifications. We report that nitro-oleic acid (OA-NO2) stimulates proMMP-7 and proMMP-9 proteolytic activity via adduction of the conserved cysteine switch domain thiolate. Biotin-labeled OA-NO2 showed this adduction occurs preferentially with latent forms of MMP, confirming a role for thiol alkylation by OA-NO2 in MMP activation. In addition to regulating pro-MMP activation, MMP expression was modulated by OA-NO2 via activation of peroxisome proliferator-activated receptor-γ. MMP-9 transcription was decreased in phorbol 12-myristate 13-acetate-stimulated THP-1 macrophages to an extent similar to that induced by the peroxisome proliferator-activated receptor-γ agonist Rosiglitazone. This was affirmed using a murine model of atherosclerosis, ApoE-/- mice, where in vivo OA-NO2 administration suppressed MMP expression in atherosclerotic lesions. These findings reveal that electrophilic fatty acid derivatives can serve as effectors during inflammation, first by activating pro-MMP proteolytic activity via alkylation of the cysteine switch domain, and then by transcriptionally inhibiting MMP expression, thereby limiting the further progression of inflammatory processes. © 2011 by The American Society for Biochemistry and Molecular Biology, Inc.