title: Role of Aβ-receptor for advanced glycation endproducts interaction in oxidative stress and cytosolic phospholipase A₂ activation in astrocytes and cerebral endothelial cells.
abstract: Blood-brain barrier (BBB) dysfunctions have been implicated in the progression of Alzheimer's disease. Cerebral endothelial cells (CECs) and astrocytes are the main cell components of the BBB. Although amyloid-β oligomers (Aβ₄₂) have been reported to mediate oxidative damage to the CECs and astrocytes and trigger the downstream mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway, the cell surface binding site for Aβ₄₂ and exact sequence of these events have yet to be elucidated. In this study, the receptor for advanced glycation endproducts (RAGE) was postulated to function as a signal transducing cell surface receptor for Aβ₄₂ to induce reactive oxygen species (ROS) generation from NADPH oxidase and trigger downstream pathways for the phosphorylation of extracellular signal-regulated kinases (ERK1/2) and cytosolic phospholipase A₂ (cPLA₂). We found that Aβ₄₂ competed with the anti-RAGE antibody (Ab(RAGE)) to bind to RAGE on the surfaces of CECs and primary astrocytes. In addition, Ab(RAGE) abrogate Aβ₄₂-induced ROS production and the colocalization between the cytosolic (p47-phox) and membrane (gp91-phox) subunits of NADPH oxidase in both cell types. Ab(RAGE) as well as NADPH oxidase inhibitor and ROS scavenger suppressed Aβ₄₂-induced ERK1/2 and cPLA₂ phosphorylation in CECs. At the same time, only Ab(RAGE), but neither NADPH oxidase inhibitor nor ROS scavenger, inhibited the ERK1/2 pathway and cPLA₂ phosphorylation in primary astrocytes. Therefore, this study demonstrates that NADPH oxidase complex assembly and ROS production are not required for Aβ₄₂ binding to RAGE at astrocytic surface leading to sequential phosphorylation of ERK1/2 and cPLA₂, and suggests the presence of two different RAGE-dependent downstream pathways in the CECs and astrocytes.
authors: Department of Biological Engineering, University of Missouri, Columbia, Missouri 65211, USA.
authors: S
authors: S
authors: Askarova
authors: X
authors: X
authors: Yang
authors: W
authors: W
authors: Sheng
authors: G Y
authors: GY
authors: Sun
authors: J C-M
authors: JC
authors: Lee
mesh_terms: D016229:Amyloid beta-Peptides / Q000378:metabolism*; D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D001812:Blood-Brain Barrier / Q000378:metabolism; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism; D002460:Cell Line; D042783:Endothelial Cells / Q000378:metabolism*; D004789:Enzyme Activation / Q000502:physiology; D005455:Fluorescent Antibody Technique; D051379:Mice; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D019255:NADPH Oxidases / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology*; D054510:Phospholipases A2, Cytosolic / Q000378:metabolism*; D011485:Protein Binding; D017382:Reactive Oxygen Species / Q000378:metabolism; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology
chemical_list: D016229:Amyloid beta-Peptides; D017382:Reactive Oxygen Species; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic; D019255:NADPH Oxidases; D054510:Phospholipases A2, Cytosolic