A lack of disease-modifying treatment strategies for Alzheimer's disease (AD) results in part from an incomplete understanding of the earliest molecular changes, when there is opportunity for reversal. A body of evidence shows that synaptic dysfunction precedes amyloid-beta (AB) deposition, suggesting that the synaptic compartment is a key site of early pathology. Accurate localization of events to terminals is difficult;therefore, our laboratory has developed methods for flow cytometry analysis of synaptosomes prepared from cryopreserved human and rodent tissue. This technique allows 1) study of populations of individual terminals (5-10,000 particles/sample) and 2) absolute quantification of synaptic AB, phosphorylated tau (p-tau), and lipid and synaptic markers in postmortem human cases and in transgenic disease models. Flow cytometry results will be verified by biochemical assays and confocal and electron microscopy. Our first studies of postmortem AD synaptic terminals showed that ~50% of terminals in AD association cortex are strongly AB-positive. Subsequent experiments have shown that similar AB accumulations occur in the Tg2576 mouse model of AD, and that the AB buildup is accompanied by a significant increase in free cholesterol and GM1 ganglioside. Our general working hypothesis is that synaptic terminal AB accumulation is a key intermediate in synaptic dysfunction prior to loss, and a potential sources or seed for AB deposition in plaques. The specific hypothesis for this project is that cholesterol in lipid raft domains enhances processing of APP to AB;therefore manipulation of terminal cholesterol via ApoE genotype and drug treatment will alter the accumulation of AB and related lipids and peptides, and will affect synaptic function. In the first Specific Aim, our goal is to determine the relationship of synaptic terminal AB to regional AD pathology, disease stage, and apoE isotype in human samples and transgenic mouse models. In the second Specific Aim, we will use dual transgenic mice to determine the effect of apoE isotype on terminals levels of AB, cholesterol and related lipids, and on synaptic function. In addition, we will study the effect of hydrophobic vs. hydrophilic statins on terminal AB accumulation. The third Specific Aim has the goal of identifying the AB peptide species in terminals along with associated changes in signaling pathways, particularly integrin focal adhesion complexes and downstream deregulation of kinase/phosphatase activity. Development of therapeutic strategies for Alzheimer's disease requires a complete understanding of the earliest pathological changes when there is still opportunity for reversal. The present project has the long term goal of identifying potential drug targets and examines pathologic changes in synaptic terminals from Alzheimer's cases and mouse models that are treated with cholesterol lowering drugs. These experiments will help us to understand how cholesterol may contribute to Alzheimer's pathology.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
5R01AG027465-05
Application #
8268141
Study Section
Cell Death in Neurodegeneration Study Section (CDIN)
Program Officer
Petanceska, Suzana
Project Start
2008-03-15
Project End
2014-02-28
Budget Start
2012-03-01
Budget End
2014-02-28
Support Year
5
Fiscal Year
2012
Total Cost
$269,427
Indirect Cost
$91,717
Name
University of California Los Angeles
Department
None
Type
Schools of Nursing
DUNS #
092530369
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
Tai, Leon M; Bilousova, Tina; Jungbauer, Lisa et al. (2013) Levels of soluble apolipoprotein E/amyloid-* (A*) complex are reduced and oligomeric A* increased with APOE4 and Alzheimer disease in a transgenic mouse model and human samples. J Biol Chem 288:5914-26
Sokolow, Sophie; Luu, Sanh H; Nandy, Karabi et al. (2012) Preferential accumulation of amyloid-beta in presynaptic glutamatergic terminals (VGluT1 and VGluT2) in Alzheimer's disease cortex. Neurobiol Dis 45:381-7
Roychaudhuri, Robin; Yang, Mingfeng; Condron, Margaret M et al. (2012) Structural dynamics of the amyloid ýý-protein monomer folding nucleus. Biochemistry 51:3957-9
Sokolow, Sophie; Henkins, Kristen M; Williams, Iris A et al. (2012) Isolation of synaptic terminals from Alzheimer's disease cortex. Cytometry A 81:248-54
Arold, Stephen; Sullivan, Patrick; Bilousova, Tina et al. (2012) Apolipoprotein E level and cholesterol are associated with reduced synaptic amyloid beta in Alzheimer's disease and apoE TR mouse cortex. Acta Neuropathol 123:39-52
Sokolow, Sophie; Luu, Sanh H; Headley, Alison J et al. (2011) High levels of synaptosomal Na(+)-Ca(2+) exchangers (NCX1, NCX2, NCX3) co-localized with amyloid-beta in human cerebral cortex affected by Alzheimer's disease. Cell Calcium 49:208-16