Endogenous Secretory Receptor for Advanced Glycation End-Products Inhibits Amyloid-β 1-42 Uptake into Mouse Brain

The cell-surface receptor for advanced glycation end-products (RAGE) has been implicated in the development of diabetic vascular complications and Alzheimer's disease. RAGE has been considered to be involved in amyloid-β_1-42 (Aβ_1-42) uptake into brain. In the present study, we demonstrate that endogenous secretory RAGE (esRAGE), a decoy form of RAGE generated by alternative RNA processing, is able to inhibit Aβ_1-42 influx into mouse brain. Surface plasmon resonance and competitive binding assays revealed that human Aβ_1-42 interacted with human esRAGE within the immunoglobulin V type region. We next examined the uptake and distribution of ¹²⁵I-labeled human Aβ_1-42 in various organs and body fluids of newly created mice overexpressing human esRAGE as well as RAGE-null and wild-type (WT) mice. The transition of the ¹²⁵I-labeled Aβ_1-42 from circulation to brain parenchyma peaked at 30 min after the injection into WT mice, but this was significantly blunted in esRAGE-overexpressing and RAGE-null mice. Significant reduction in ¹²⁵I-labeled Aβ_1-42-derived photo-stimulated luminescence were marked in ventricles, cerebral cortex, hippocampus, especially CA1 and CA3 regions, putamen, and thalamus. The results thus suggest the potential of esRAGE in protection against the development of Alzheimer's disease.