The receptor for advanced glycation end products (RAGE), a newly-identified member of the immunoglobulin superfamily, mediates interactions of advanced glycation end product (AGE)-modified proteins with endothelium and other cell types. Survey of normal tissues demonstrated RAGE expression in situations in which accumulation of AGEs would be unexpected, leading to the hypothesis that under physiologic circumstances, RAGE might mediate interaction with ligands distinct from AGEs. Sequential chromatography of bovine lung extract identified polypeptides with M r values of Ϸ12,000 (p12) and Ϸ23,000 (p23) which bound RAGE. NH 2 -terminal and internal protein sequence data for p23 matched that reported previously for amphoterin. Amphoterin purified from rat brain or recombinant rat amphoterin bound to purified sRAGE in a saturable and dose-dependent manner, blocked by anti-RAGE IgG or a soluble form of RAGE (sRAGE). Cultured embryonic rat neurons, which express RAGE, displayed dose-dependent binding of 125 I-amphoterin which was prevented by blockade of RAGE using antibody to the receptor or excess soluble receptor (sRAGE). A functional correlate of RAGE-amphoterin interaction was inhibition by anti-RAGE F(ab) 2 and sRAGE of neurite formation by cortical neurons specifically on amphoterin-coated substrates. Consistent with a potential role for RAGEamphoterin interaction in development, amphoterin and RAGE mRNA/antigen were co-localized in developing rat brain. These data indicate that RAGE has physiologically relevant ligands distinct from AGEs which are likely, via their interaction with the receptor, to participate in physiologic processes outside of the context of diabetes and accumulation of AGEs.Incubation of proteins or lipids with aldose sugars results in nonenzymatic glycation and oxidation (1-7). Following formation of the reversible early glycation products, Schiff bases and Amadori products, further complex molecular rearrangements result in irreversible advanced glycation end products (AGEs). 1Factors favoring nonenzymatic glycation include delayed protein turnover, as in amyloidoses, accumulation of macromolecules with high lysine content, and situations with elevated glucose levels, as in diabetes. AGE formation occurs during normal aging, and at an accelerated rate in diabetes, in which their accumulation in the plasma and vessel wall has been speculated to underlie the pathogenesis of vasculopathy (1, 2, 4).One of the principal means through which AGEs impact on cellular elements is through interaction with cellular binding proteins. Although there are several possible cell-associated polypeptides with which AGEs might interact (8, 9), our work has focussed on the receptor for AGEs (RAGE), as its expression in endothelium, vascular smooth muscle, mononuclear phagocytes, and the central nervous system suggests strategic loci for interaction with the glycated ligands (10, 11). The potential pathophysiologic relevance of AGE-RAGE interaction was emphasized by studies demonstrating that blockade of RAGE pr...

Vascular cell adhesion molecule-1 (VCAM-1), an inducible cell-cell recognition protein on the endothelial cell surface (EC), has been associated with early stages of atherosclerosis. In view of the accelerated vascular disease observed in patients with diabetes, and the enhanced expression of VCAM-1 in diabetic rabbits, we examined whether irreversible advanced glycation endproducts (AGEs), could mediate VCAM-1 expression by interacting with their endothelial cell receptor (receptor for AGE, RAGE). Exposure of cultured human ECs to AGEs induced expression of VCAM-1, increased adhesivity of the monolayer for Molt-4 cells, and was associated with increased levels of VCAM-1 transcripts. The inhibitory effect of anti-RAGE IgG, a truncated form of the receptor (soluble RAGE) or N-acetylcysteine on VCAM-1 expression indicated that AGE-RAGE-induced oxidant stress was central to VCAM-1 induction. Electrophoretic mobility shift assays on nuclear extracts from AGE-treated ECs showed induction of specific DNA binding activity for NF-kB in the VCAM-1 promoter, which was blocked by anti-RAGE IgG or N-acetylcysteine. Soluble VCAM-1 antigen was elevated in human diabetic plasma. These data are consistent with the hypothesis that AGE-RAGE interaction induces expression of VCAM-1 which can prime diabetic vasculature for enhanced interaction with circulating monocytes. (J. Clin. Invest. 1995.96:1395-1403

Islet amyloidosis by IAPP contributes to pancreatic β-cell death in diabetes, but the nature of toxic IAPP species remains elusive. Using concurrent time-resolved biophysical and biological measurements, we define the toxic species produced during IAPP amyloid formation and link their properties to induction of rat INS-1 β-cell and murine islet toxicity. These globally flexible, low order oligomers upregulate pro-inflammatory markers and induce reactive oxygen species. They do not bind 1-anilnonaphthalene-8-sulphonic acid and lack extensive β-sheet structure. Aromatic interactions modulate, but are not required for toxicity. Not all IAPP oligomers are toxic; toxicity depends on their partially structured conformational states. Some anti-amyloid agents paradoxically prolong cytotoxicity by prolonging the lifetime of the toxic species. The data highlight the distinguishing properties of toxic IAPP oligomers and the common features that they share with toxic species reported for other amyloidogenic polypeptides, providing information for rational drug design to treat IAPP induced β-cell death.DOI: http://dx.doi.org/10.7554/eLife.12977.001

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An important component of amyloid fibrils in dialysisrelated amyloidosis is a form of ␤ 2 microglobulin modified with advanced glycation end products (AGEs) of the Maillard reaction, known as AGE-␤ 2 M. We demonstrate here that the interaction of AGE-␤ 2 M with mononuclear phagocytes (MPs), cells important in the pathogenesis of the inflammatory arthropathy of dialysis-related amyloidosis, is mediated by the receptor for AGEs, or RAGE.125 I-AGE-␤ 2 M bound to immobilized RAGE or to MPs in a specific, dose-dependent manner ( K d Ϸ 53.5 and Ϸ 81.6 nM, respectively), a process inhibited in the presence of RAGE blockade. AGE-␤ 2 M-mediated monocyte chemotaxis was prevented by excess sRAGE or anti-RAGE IgG. Induction of tumor necrosis factor-␣ (TNF) expression by MPs exposed to AGE-␤ 2 M resulted from engagement of RAGE, as appearances of TNF transcripts and TNF antigen release into culture supernatants were prevented by addition of sRAGE, a process mediated, at least in part, by oxidant stress. AGE-␤ 2 M reduced cytochrome c and the elaboration of TNF by MPs was inhibited by N -acetylcysteine. Consistent with these data, immunohistochemical studies of AGE-laden amyloid deposits of a long-term hemodialysis patient revealed positive staining for RAGE in the MPs infiltrating these lesions. These data indicate that RAGE is a central binding site for AGEs formed in vivo and suggest that AGE-␤ 2 M-MP-RAGE interaction likely contributes to the initiation of an inflammatory response in amyloid deposits of long-term hemodialysis patients, a process which may ultimately lead to bone and joint destruction. ( J. Clin. Invest. 98:1088-1094.) Key words: glycated proteins • cytokines • long-term hemodialysis patients • monocyte • amyloidosis IntroductionProteins or lipids exposed to aldose sugars undergo nonenzymatic glycation and oxidation (1-7). Initially, the reversible early glycation adducts form, the best known of which is hemoglobin A 1c, used as an index of glycemic control in diabetic patients. After further complex molecular rearrangements, the irreversible advanced glycation end products (AGEs) 1 form. Conditions favoring AGE formation include those in which protein/lipid turnover is prolonged or delayed on lysine-rich structures, especially in the setting of elevated levels of aldose sugars, such as in diabetes. AGE formation can occur even in the euglycemic state, as in hypercholesterolemic rabbits without diabetes, in which macromolecules are trapped in the expanded neointima in atherosclerosis-prone animals (8).While the generation of AGEs is particularly likely in the diabetic milieu given relatively sustained hyperglycemia (1-4), the tendency toward generation of AGEs is also favored on long-lived proteins, such as those central in the pathogenesis of amyloidoses. In Alzheimer's disease, AGE modification occurs on components of the intracellular neurofibrillary tangles and in extracellular amyloid-␤ peptide (9-11). In a different context, renal failure presents a unique pathophysiological setting for the d...