Activation of the Receptor for Advanced Glycation End Products Triggers a p21 -dependent Mitogen-activated Protein Kinase Pathway Regulated by Oxidant Stress

Abstract

Advanced glycation end products (AGEs) exert their cellular effects on cells by interacting with specific cellular receptors, the best characterized of which is the receptor for AGE (RAGE). The transductional processes by which RAGE ligation transmits signals to the nuclei of cells is unknown and was investigated. AGE-albumin, a prototypic ligand, activated p21 ras in rat pulmonary artery smooth muscle cells that express RAGE, whereas nonglycated albumin was without effect. MAP kinase activity was enhanced at concentrations of AGE-albumin, which activated p21 ras and NF-B. Depletion of intracellular glutathione rendered cells more sensitive to AGE-mediated activation of this signaling pathway. In contrast, signaling was blocked by preventing p21 ras from associating with the plasma membrane or mutating Cys 118 on p21 ras to Ser. Signaling was receptor-dependent, because it was prevented by blocking access to RAGE with either anti-RAGE IgG or by excess soluble RAGE. These data suggest that RAGE-mediated induction of cellular oxidant stress triggers a cascade of intracellular signals involving p21 ras and MAP kinase, culminating in transcription factor activation. The molecular mechanism that triggers this pathway likely involves oxidant modification and activation of p21 ras .In the presence of aldoses, proteins become nonenzymatically glycated and oxidized (1-3). This initially reversible glycation is followed by further irreversible rearrangements leading to a class of permanently modified proteins known as advanced glycation end products (AGEs).1 Although glycated proteins are found at low levels in normal individuals during aging, significantly higher levels are found in certain disease states such as diabetes and renal failure (4, 5). We have identified a cellular receptor for AGEs, termed RAGE, which exhibits a wide tissue distribution (6 -9). We have recently demonstrated the enhanced presence of RAGE in vascular smooth muscle of diabetic vasculature (renal arterial vessel) compared with a similar sized vessel from a nondiabetic age-matched control. These areas of enhanced RAGE immunoreactivity colocalize with enhanced immunostaining for AGE-reactive epitopes (10). Our previous data in endothelial cells and in vivo demonstrated that interaction of AGEs with RAGE results in triggering a range of cellular responses, including transcription factor activation and changes in gene expression (11)(12)(13)(14). However, the means by which a signal reflecting AGE engagement of RAGE is transmitted to the nucleus is not known. Given the enhanced expression of AGE and RAGE in diabetic vascular smooth muscle, we focused on elucidating the signaling pathways in smooth muscle cells that are triggered upon ligation of RAGE by AGE-albumin, a prototypical ligand.Recent evidence supports a role for reactive oxygen species in mediating signaling by several receptor systems (15-21). For example, platelet-derived growth factor has recently been shown to stimulate H 2 O 2 production in vascular smooth muscle cells (15). When pro...

Cognitive dysfunction associates with white matter hyperintensities and subcortical atrophy on magnetic resonance imaging of the elderly diabetes mellitus Japanese elderly diabetes intervention trial (J‐EDIT)

“…Hyperglycemia causes oxidative stress via the polyol pathway, enhances advanced glycation end products (AGE), and increases lipid peroxidation and imbalances in the generation of reactive oxygen species and their scavengers [53,54]. N ε -Carboxymethyllysine (CML), the most prominent AGE product, is crucially involved in the development of diabetic microangiopathy [55], and the level of CML expression is high in the blood vessels and brain of diabetic patients, but low in aging controls [56]. Oxidative stress has also been implicated in the pathophysiology of Alzheimer's disease and hypoxic brain insults [57][58][59].…”

RAGE and arthritis: the G82S polymorphism amplifies the inflammatory response

“…Incubation of mock-transfected CHO cells with a physiologically-relevant concentration of EN-RAGE, 4 10 g/ml, did not significantly increase intensity of the bands corresponding to phosphorylated MEK 1/2 or p44/42 MAP kinases [22][23] (Figure 4d,e, respectively; lanes 1-5). However, exposure of RAGE 82G CHO transfectants to EN-RAGE increased by 2.2-fold and 1.9-fold phosphorylated MEK 1/2 and p44/42 MAP kinases, compared with cultures incubated with BSA alone (P Ͻ 0.01; Figure 4d,e respectively; lanes 7 and 6).…”

Articular chondrocytes express the receptor for advanced glycation end products: Potential role in osteoarthritis

“…In order to provide further evidence that chondrocytes express functional RAGE, cells were first treated with S100B, which is a known RAGE ligand (7,8) and which has previously been described in chondrocytes (9). Treatment with S100B resulted in phosphorylation of the ERK-1/2 MAP kinase and the p65 subunit of NF-B ( Figure 5), both of which are well-characterized mediators of RAGE signaling (12,13). Consistent with RAGE stimulation by S100B, the phosphorylation of ERK and NF-B was inhibited by sRAGE but not by sTNFR.…”

“…RAGE signaling activated by AGE binding, S100 proteins, or HMGB-1 induces oxidative stress and activates MAP kinase signaling, leading downstream to increased NF-B activity (12,13). Oxidative damage (14) and activation of MAP kinases (15,16) have been reported in OA cartilage, and signaling that results in increased NF-B could contribute to cartilage degradation through up-regulation of matrix metalloproteinase (MMP) expression (17).…”