Abstract
Apolipoprotein E (ApoE) genotype is a powerful genetic modifier of Alzheimer's disease (AD). The ApoE4 isoform significantly reduces the mean age-of-onset of dementia through unknown mechanisms. Here, we show that ApoE4 selectively impairs synaptic plasticity and NMDA receptor phosphorylation by Reelin, a regulator of brain development and modulator of synaptic strength. ApoE4 reduces neuronal surface expression of Apoer2, a dual function receptor for ApoE and for Reelin, as well as NMDA and AMPA receptors by sequestration in intracellular compartments, thereby critically reducing the ability of Reelin to enhance synaptic glutamate receptor activity. As a result, the ability of Reelin to prevent LTP suppression by extracts from AD-afflicted human brains in hippocampal slices from knockin mice expressing the human ApoE4 isoform is severely impaired. These findings show an isoform-specific role of ApoE in the localization and intracellular trafficking of lipoprotein and glutamate receptors and thereby reveal an alternative mechanism by which ApoE4 may accelerate onset of dementia and neuronal degeneration by differentially impairing the maintenance of synaptic stability.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Alzheimer Disease / genetics
-
Alzheimer Disease / metabolism
-
Animals
-
Apolipoprotein E4 / genetics
-
Apolipoprotein E4 / metabolism*
-
Brain / metabolism
-
Cell Adhesion Molecules, Neuronal / metabolism
-
Extracellular Matrix Proteins / metabolism
-
Humans
-
In Vitro Techniques
-
LDL-Receptor Related Proteins
-
Long-Term Potentiation
-
Low Density Lipoprotein Receptor-Related Protein-1 / metabolism*
-
Mice
-
Mice, Transgenic
-
Models, Neurological
-
Nerve Tissue Proteins / metabolism
-
Neuronal Plasticity / physiology*
-
Receptors, AMPA / metabolism
-
Receptors, Glutamate / metabolism*
-
Receptors, Lipoprotein / metabolism
-
Receptors, N-Methyl-D-Aspartate / metabolism
-
Recombinant Proteins / genetics
-
Recombinant Proteins / metabolism
-
Reelin Protein
-
Serine Endopeptidases / metabolism
Substances
-
Apolipoprotein E4
-
Cell Adhesion Molecules, Neuronal
-
Extracellular Matrix Proteins
-
LDL-Receptor Related Proteins
-
Low Density Lipoprotein Receptor-Related Protein-1
-
Nerve Tissue Proteins
-
Receptors, AMPA
-
Receptors, Glutamate
-
Receptors, Lipoprotein
-
Receptors, N-Methyl-D-Aspartate
-
Recombinant Proteins
-
Reelin Protein
-
low density lipoprotein receptor-related protein 8
-
RELN protein, human
-
Reln protein, mouse
-
Serine Endopeptidases