Requirement for p38 and p44/p42 mitogen-activated protein kinases in RAGE-mediated nuclear factor-kappa B transcriptional activation and cytokine secretion

Advanced glycation end product (AGE) activation of the signal-transducing r eceptor for AGE (RAGE) has been linked to a proinflammatory phenotypic chan ge within cells. However, the precise intracellular signaling pathways invo lved have not been elucidated. We demonstrate here that human serum albumin modified with N-epsilon-(carboxymethyl)lysine (CML), a major AGE adduct th at progressively accumulates with aging, diabetes, and renal failure, induc ed nuclear factor (NF)-kappaB-driven reporter gene expression in human mono cytic THP-1 cells. The NF-kappaB response was blocked with a synthetic pept ide corresponding to the putative ligand-binding domain of RAGE, with anti- RAGE antiserum, and by coexpression of truncated receptors lacking the intr acellular domain. Signal transduction from RAGE to NF-kappaB involved the g eneration of reactive oxygen species, since reporter gene expression was bl ocked with the antioxidant N-acetyl-L-cysteine. CML-modified albumin produc ed rapid transient activation of tyrosine phosphorylation, extracellular si gnal-regulated kinase 1 and 2, and p38 mitogen-activated protein kinase (MA PK), but not c-Jun NH2-terminal kinase. RAGE-mediated NF-kappaB activation was suppressed by the selective p38 MAPK inhibitor SB203580 and by coexpres sion of a kinase-dead p38 dominant-negative mutant. Activation of NF-kappaB by CML-modified albumin increased secretion of proinflammatory cytokines ( tumor necrosis factor-alpha, interleukin-1 beta, and monocyte chemoattracta nt protein-1) severalfold, and inhibition of p38 MAPK blocked these increas es. These results indicate that p38 MAPK activation mediates RAGE-induced N F-kappaB-dependent secretion of proinflammatory cytokines and suggest that accelerated inflammation may be a consequence of cellular activation induce d by this receptor.