N-methyl-D-aspartate receptors are required for synaptic targeting of Alzheimer's toxic amyloid-β peptide oligomers.
Soluble amyloid-β peptide (Aβ) oligomers, known to accumulate in Alzheimer's disease brains, target excitatory post-synaptic terminals. This is thought to trigger synapse deterioration, a mechanism possibly underlying memory loss in early stage Alzheimer's disease. A major unknown is the identity of the receptor(s) targeted by oligomers at synapses. Because oligomers have been shown to interfere with N-methyl-d-aspartate receptor (NMDAR) function and trafficking, we hypothesized that NMDARs might be required for oligomer binding to synapses. An amplicon vector was used to knock-down NMDARs in mature hippocampal neurons in culture, yielding 90% reduction in dendritic NMDAR expression and blocking neuronal oxidative stress induced by Aβ oligomers, a pathological response that has been shown to be mediated by NMDARs. Remarkably, NMDAR knock-down abolished oligomer binding to dendrites, indicating that NMDARs are required for synaptic targeting of oligomers. Nevertheless, oligomers do not appear to bind directly to NMDARs as indicated by the fact that both oligomer-attacked and non-attacked neurons exhibit similar surface levels of NMDARs. Furthermore, pre-treatment of neurons with insulin down-regulates oligomer-binding sites in the absence of a parallel reduction in surface levels of NMDARs. Establishing that NMDARs are key components of the synaptic oligomer binding complex may illuminate the development of novel approaches to prevent synapse failure triggered by Aβ oligomers.
Decker
Helena
H
Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
Jürgensen
Sofia
S
Adrover
Martin F
MF
Brito-Moreira
Jordano
J
Bomfim
Theresa R
TR
Klein
William L
WL
Epstein
Alberto L
AL
De Felice
Fernanda G
FG
Jerusalinsky
Diana
D
Ferreira
Sergio T
ST
D000544:Alzheimer Disease / Q000378:metabolism* / Q000473:pathology; D016229:Amyloid beta-Peptides / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity; D000818:Animals; D002478:Cells, Cultured; D055785:Gene Knockdown Techniques; D006624:Hippocampus / Q000378:metabolism / Q000473:pathology; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity; D011485:Protein Binding / Q000502:physiology; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000172:deficiency / Q000502:physiology*; D013569:Synapses / Q000378:metabolism* / Q000473:pathology
D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; D016194:Receptors, N-Methyl-D-Aspartate; C075222:amyloid beta-protein (1-42)