Loss of synapses is the variable that currently appears to correlate best with the degree of dementia in Alzheimer's disease (AD). Based on the cytoskeletal disruption associated with the formation of neurofibrillary tangles (NFT), and their constituent, """"""""abnormally"""""""" phosphorylated tau, we hypothesize that neurons with NFT, rather than their adjacent tangle-free neurons, are at least partially responsible for this loss of synapses (whether this precedes neuron death remains an open question). Our focus in this proposal is to test hypotheses related the effects(s) (or lack thereof) of NFT and of tau phosphorylated at different sites (and combinations of sites) on the expression of messages related to synaptic and neuronal function: synaptophysin, GAP-43, heat shock proteins, cathepsins. Tau has 21 potential phosphorylation sites. The studies we propose are driven by a model of tau function in which the microtubule binding domain (the repeat region) is surrounded by """"""""jaws"""""""" regions which make important contributions to tau promotion of microtubule assembly. We will use in situ hybridization for synaptophysin and other selected messages to determine the molecular status of single neurons combined with double immunocytochemistry (ICC) to define classes of neurons. We will compare grain counts over single neurons from the classes of neurons revealed by antibody combinations: Three general classes of neurons will appear in AD brain: 1) with NFT (phospho-tau may also be apparent in these neurons), 2) without NFT but with phospho-tau at defined sites and combinations of sites, and 3) neither NFT nor phospho-tau. Neurons without evidence of NFT or phospho-tau will be sampled from control brain. Disease-free control and AD brain sections will be processed side-by-side on the same slides for quantitative comparison. The general hypotheses to be tested are, briefly: Hypothesis I: Neurons with NFT will have decreased message for proteins related synaptic structure and function and the growth cone. Hypothesis II: Tau phosphorylation in the """"""""jaws"""""""" region will have a greater influence on expression of synaptic and stress related messages than will tau phosphorylation at Ser 262 in the repeat, microtubule binding region of tau. Hypothesis III: Neurons with NFT or abnormally phosphorylated tau will have increased levels of message for proteins related to cellular stress. Hypothesis IV: There will be """"""""unaffected"""""""" neurons in AD brain that our measures will not distinguish from homologous neurons in control brain.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
3R01AG014441-04S1
Application #
6345444
Study Section
Special Emphasis Panel (ZRG1 (01))
Program Officer
Snyder, D Stephen
Project Start
1997-05-01
Project End
2002-04-30
Budget Start
2000-09-16
Budget End
2001-04-30
Support Year
4
Fiscal Year
2000
Total Cost
$100,000
Indirect Cost
Name
University of Rochester
Department
Neurosciences
Type
Schools of Dentistry
DUNS #
208469486
City
Rochester
State
NY
Country
United States
Zip Code
14627
Coleman, Paul; Kurlan, Roger; Crook, Richard et al. (2004) A new presenilin Alzheimer's disease case confirms the helical alignment of pathogenic mutations in transmembrane domain 5. Neurosci Lett 364:139-40
Coleman, Paul D; Yao, Pamela J (2003) Synaptic slaughter in Alzheimer's disease. Neurobiol Aging 24:1023-7
Yao, Pamela J; O'Herron, Timothy M; Coleman, Paul D (2003) Immunohistochemical characterization of clathrin assembly protein AP180 and synaptophysin in human brain. Neurobiol Aging 24:173-8
Yao, Pamela J; Zhu, Min; Pyun, Eunice I et al. (2003) Defects in expression of genes related to synaptic vesicle trafficking in frontal cortex of Alzheimer's disease. Neurobiol Dis 12:97-109
Yao, Pamela J; Coleman, Paul D; Calkins, David J (2002) High-resolution localization of clathrin assembly protein AP180 in the presynaptic terminals of mammalian neurons. J Comp Neurol 447:152-62
Yao, P J; Weimer, J M; O'Herron, T M et al. (2000) Clathrin assembly protein AP-2 is detected in both neurons and glia, and its reduction is prominent in layer II of frontal cortex in Alzheimer's disease. Neurobiol Aging 21:921-9
Utal, A K; Coleman, P D (1999) Non-HPLC separation of water-soluble choline metabolites by two-dimensional high voltage electrophoresis and thin layer chromatography. J Neurosci Methods 90:13-21
Morsch, R; Simon, W; Coleman, P D (1999) Neurons may live for decades with neurofibrillary tangles. J Neuropathol Exp Neurol 58:188-97
Yao, P J; Morsch, R; Callahan, L M et al. (1999) Changes in synaptic expression of clathrin assembly protein AP180 in Alzheimer's disease analysed by immunohistochemistry. Neuroscience 94:389-94
Chow, N; Cox, C; Callahan, L M et al. (1998) Expression profiles of multiple genes in single neurons of Alzheimer's disease. Proc Natl Acad Sci U S A 95:9620-5

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