title: Screening for Small Molecule Inhibitors of Statin-Induced APP C-terminal Toxic Fragment Production.
abstract: Alzheimer's disease (AD) is characterized by neuronal and synaptic loss. One process that could contribute to this loss is the intracellular caspase cleavage of the amyloid precursor protein (APP) resulting in release of the toxic C-terminal 31-amino acid peptide APP-C31 along with the production of APPΔC31, full-length APP minus the C-terminal 31 amino acids. We previously found that a mutation in APP that prevents this caspase cleavage ameliorated synaptic loss and cognitive impairment in a murine AD model. Thus, inhibition of this cleavage is a reasonable target for new therapeutic development. In order to identify small molecules that inhibit the generation of APP-C31, we first used an APPΔC31 cleavage site-specific antibody to develop an AlphaLISA to screen several chemical compound libraries for the level of N-terminal fragment production. This antibody was also used to develop an ELISA for validation studies. In both high throughput screening (HTS) and validation testing, the ability of compounds to inhibit simvastatin- (HTS) or cerivastatin- (validation studies) induced caspase cleavage at the APP-D720 cleavage site was determined in Chinese hamster ovary (CHO) cells stably transfected with wildtype (wt) human APP (CHO-7W). Several compounds, as well as control pan-caspase inhibitor Q-VD-OPh, inhibited APPΔC31 production (measured fragment) and rescued cell death in a dose-dependent manner. The effective compounds fell into several classes including SERCA inhibitors, inhibitors of Wnt signaling, and calcium channel antagonists. Further studies are underway to evaluate the efficacy of lead compounds - identified here using cells and tissues expressing wt human APP - in mouse models of AD expressing mutated human APP, as well as to identify additional compounds and determine the mechanisms by which they exert their effects.
authors.affiliation: Bredesen Lab, Buck Institute for Research on Aging, Novato CA, USA.
authors.forename: Karen S
authors.initials: KS
authors.lastname: Poksay
authors.affiliation: Cancer Metabolism and Signaling Networks Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla CA, USA.
authors.forename: Douglas J
authors.initials: DJ
authors.lastname: Sheffler
authors.affiliation: Bredesen Lab, Buck Institute for Research on Aging, NovatoCA, USA; Drug Discovery Lab, Department of Neurology, University of California, Los AngelesCA, USA.
authors.forename: Patricia
authors.initials: P
authors.lastname: Spilman
authors.affiliation: Drug Discovery Lab, Department of Neurology, University of California, Los Angeles CA, USA.
authors.forename: Jesus
authors.initials: J
authors.lastname: Campagna
authors.affiliation: Drug Discovery Lab, Department of Neurology, University of California, Los Angeles CA, USA.
authors.forename: Barbara
authors.initials: B
authors.lastname: Jagodzinska
authors.affiliation: Bredesen Lab, Buck Institute for Research on Aging, Novato CA, USA.
authors.forename: Olivier
authors.initials: O
authors.lastname: Descamps
authors.affiliation: Bredesen Lab, Buck Institute for Research on Aging, Novato CA, USA.
authors.forename: Olivia
authors.initials: O
authors.lastname: Gorostiza
authors.affiliation: Bredesen Lab, Buck Institute for Research on Aging, Novato CA, USA.
authors.forename: Alex
authors.initials: A
authors.lastname: Matalis
authors.affiliation: Enzo Life Sciences, Inc., Farmingdale NY, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Mullenix
authors.affiliation: Bredesen Lab, Buck Institute for Research on Aging, NovatoCA, USA; Drug Discovery Lab, Department of Neurology, University of California, Los AngelesCA, USA.
authors.forename: Dale E
authors.initials: DE
authors.lastname: Bredesen
authors.affiliation: Cancer Metabolism and Signaling Networks Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla CA, USA.
authors.forename: Nicholas D P
authors.initials: ND
authors.lastname: Cosford
authors.affiliation: Drug Discovery Lab, Department of Neurology, University of California, Los Angeles CA, USA.
authors.forename: Varghese
authors.initials: V
authors.lastname: John
keywords: AD – Alzheimer’s disease; APP – amyloid precursor protein; APP-C31 –C-terminal 31 amino acid fragment of APP; APPΔC31 – N-terminal APP fragment minus C-terminal 31 amino acids (alphabetical); statins