| Receptor for Advanced Glycation End-products (RAGE) is a pattern-recognition receptor of the immunoglobulin superfamily that contains three extracellular immunoglobulin-like domains, a single transmembrane segment and a short cytoplasmic tail, and it binds multiple structurally distinct ligands including AGEs, S100/calgranulin proteins, HMGB1 and amyloid-β to couple danger signals with intracellular inflammatory cascades. Ligand binding to the extracellular V-type immunoglobulin domain induces conformational changes that, through the transmembrane region and cytoplasmic tail, recruit adaptor molecules and activate downstream signaling pathways such as NF‑κB, JAK/STAT and MAPKs including p38 and JNK, which increase transcription of pro-inflammatory cytokines, adhesion molecules and oxidative stress mediators. In the nervous system, RAGE is expressed on neurons, microglia, astrocytes and brain endothelial cells, where its engagement by AGEs, S100 proteins or amyloid-β drives production of TNF‑α, IL‑1β and reactive oxygen species and amplifies neuroinflammatory responses, and RAGE signaling contributes to intraneuronal amyloid-β accumulation through effects on APP processing and secretase activity. Structural variants include full-length membrane RAGE and soluble forms such as sRAGE generated by alternative splicing or proteolytic shedding; sRAGE retains ligand-binding capacity but lacks the transmembrane and cytoplasmic domains, acting as a decoy that can sequester ligands and modulate the intensity of signaling through membrane RAGE. At the blood–brain barrier, RAGE participates in transport of circulating amyloid-β into the brain, counterbalancing LRP1-mediated efflux, and this influx function influences the steady-state levels of amyloid-β in brain parenchyma and contributes to plaque formation and synaptic dysfunction when RAGE signaling and ligand load are increased. In vascular and metabolic tissues, AGEs formed under chronic hyperglycemia bind RAGE and induce endothelial activation, oxidative stress and expression of adhesion molecules, linking RAGE signaling to diabetic vasculopathy, atherosclerotic lesion development and cardiovascular complications through sustained NF‑κB-driven inflammatory gene expression. RAGE–ligand interactions also affect smooth muscle cell migration and proliferation and promote remodeling of vascular walls, while in peripheral nerves and glia AGEs–RAGE signaling participates in diabetic neuropathy and other neurodegenerative conditions by enhancing cytokine production and oxidative damage. Tissue distribution studies show high RAGE expression in lung and significant levels in heart and brain, with inducible upregulation under stress and inflammation, and alternative splicing and shedding regulate the balance between signaling-competent membrane RAGE and soluble decoy forms, influencing ligand availability and downstream pathway activation in a context-dependent manner. Across neurodegenerative diseases such as Alzheimer’s, Parkinson’s and amyotrophic lateral sclerosis, RAGE signaling networks intersect with amyloid-β and tau pathology, mitochondrial dysfunction and synaptic failure, and pharmacologic or biological RAGE inhibitors that block ligand binding or signaling have shown preclinical efficacy in reducing neuroinflammation, oxidative stress and cognitive decline, supporting the importance of this receptor as a mechanistic node in AGEs- and damage-associated ligand-driven pathology. |
