Numerous lines of evidence support the hypothesis that targeting A[342 is an ideal therapeutic strategy to prevent and/or treat Alzheimer's disease (AD), the major cause of dementia among the elderly. Chemicals called y-secretase modulators (GSMs), are being developed as AD therapeutics because they are able to selectively decrease Ap42. The first GSMs to be discovered were non-steroidal antiinflammatory drugs (NSAIDs), which lower Ap42 without inhibition of APP processing. As a whole GSMs minimally alter total Abeta production and instead shift where gamma-secretase cleaves Abeta. The mechanism of GSMs is still unknown although different explanations for their activity have been proposed including: 1) allosteric binding to y-secretase 2) inhibition of the Rho-ROCK signaling pathway 3) conformational changes in presenilin or 4) decreased dimerization of APP. We have recently discovered using novel GSM photoaffinity probes that these drugs do not label the y-secretase enzyme but instead modulate cleavage by binding to the substrate, APP. We hypothesize that binding of APP by GSMs shifts the position of APP-CTF in the membrane resulting in altered gamma-secretase cleavage. This hypothesis will be tested through the following specific aims: 1) investigate how substrate targeting by GSMs produces a shift in the cleavage pattern of Ap using a combination of molecular biology and protein biochemistry 2) determine the specificity of GSMs for affecting APP proteolysis by y-secretase in comparison to other substrates and 3) incorporate unnatural amino acids to study proteolysis of APPCTF by y-secretase. These studies will provide additional insight into how NSAIDs and other GSMs shift A(3 cleavage and how they exert their protective effects in vivo. This work will also guide future efforts to design more potent GSMs which will be useful as chemical probes for understanding the biology of ysecretase and as potential therapeutics for Alzheimer's disease.

Public Health Relevance

Alzheimer's disease (AD) is the most common type of dementia afflicting the elderly with no known cure, ysecretase modulators (GSMs) are a promising class of drugs under investigation to treat AD. The proposed research will provide critical insight into how GSMs work and may ultimately lead to improved AD therapeutics.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Transition Award (R00)
Project #
5R00AG032362-05
Application #
8605484
Study Section
Special Emphasis Panel (NSS)
Program Officer
Petanceska, Suzana
Project Start
2009-04-01
Project End
2015-01-31
Budget Start
2014-02-01
Budget End
2015-01-31
Support Year
5
Fiscal Year
2014
Total Cost
$212,863
Indirect Cost
$75,532
Name
Emory University
Department
Pharmacology
Type
Schools of Medicine
DUNS #
066469933
City
Atlanta
State
GA
Country
United States
Zip Code
30322
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