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P4‐433: Identification of first and second generation ATase1 and ATase2 inhibitors that reduce BACE1 levels and Aβ generation
Author(s) -
Ding Yun,
Puglielli Luigi,
Ko Mi Hee,
Pehar Mariana
Publication year - 2011
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2011.09.129
Subject(s) - acetylation , in vitro , acetyltransferases , acetyltransferase , chemistry , histone acetyltransferases , cleavage (geology) , biochemistry , microbiology and biotechnology , biology , gene , paleontology , fracture (geology)
Background: Our group has recently identified a novel form of post-translational regulation that affects both levels and activity of BACE1 (Biochem J 2007;407:383). Specifically, we discovered that nascent BACE1 is transiently acetylated in the lumen of the ER by two acetyltransferases, which we named ATase1 and ATase2 (J Biol Chem 2009;284:2482). The acetylated intermediates of nascent BACE1 are able to complete maturation whereas non-acetylated intermediates are rapidly degraded (EMBO Rep 2008;9:916). Consistently, up-regulation of ATase1 and ATase2 increases BACE1 levels and Abeta generation while down-regulation has the opposite effects. Additionally, the expression levels of both acetyltransferases were found highly increased in the temporal cortex of late-onset AD patients. Methods: As part of our current efforts, we have developed a fluorescent assay that efficiently monitors the acetyltransferase activity of ATase1 and ATase2 in vitro. The assay was used to screen a single library of 14,400 compounds. Results: The screen identified 186 compounds able to inhibit ATase1 and ATase2 in vitro. Each compound was then screened for cytotoxic properties. Of the above 186 compounds, only 30 did not cause significant cytotoxicity. The above 30 compounds were individually screened on human neuroglioma (H4) cells for their ability to reduce the levels of BACE1 and the generation of Abeta. Two different compounds produced significant changes. Second generation chemical derivatives were generated to assess structure-dependent activity; preliminary biochemical characterization was also performed. Successful compounds were able to down-regulate the expression levels of BACE1 and reduce the beta cleavage of APP. The mechanism of action involves competitive inhibition as well as generation of kinetically unstable intermediates of the ATases that are rapidly degraded. The effect on BACE1 and APP processing was dose-dependent and already detectable at concentration ofw0.5-2mM. Conclusions: In conclusion, we have discovered novel compounds/small molecules that are able to down-regulate the levels of BACE1 and the rate of Abeta generation by affecting the enzymatic activity of the recently identified ATase1 and ATase2. Because of the role that BACE1 plays in the pathogenesis of AD, biochemical approaches targeting the recently discovered ER-based acetyltransferases may lead to novel strategies for the prevention and/or therapy of AD.