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J Alzheimers Dis. 2019;67(3):1089-1106. doi: 10.3233/JAD-180923.

Small Molecule Amyloid-β Protein Precursor Processing Modulators Lower Amyloid-β Peptide Levels via cKit Signaling.

Author information

1
Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA.
2
Department of Chemistry, Boston University, Boston, MA, USA.
3
Center for Molecular Discovery (BU-CMD), Boston University, Boston, MA, USA.
4
Department of Biology, Boston University, Boston, MA, USA.
5
Department of Neuroscience, Boston University, Boston, MA, USA.
6
Department of Biomedical Engineering, Boston University, Boston, MA, USA.
7
Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, USA.
8
Bedford Geriatric Research Education Clinical Center, Bedford VA Medical Center, Bedford, MA, USA.
9
Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI, USA.

Abstract

Alzheimer's disease (AD) is characterized by the accumulation of neurotoxic amyloid-β (Aβ) peptides consisting of 39-43 amino acids, proteolytically derived fragments of the amyloid-β protein precursor (AβPP), and the accumulation of the hyperphosphorylated microtubule-associated protein tau. Inhibiting Aβ production may reduce neurodegeneration and cognitive dysfunction associated with AD. We have previously used an AβPP-firefly luciferase enzyme complementation assay to conduct a high throughput screen of a compound library for inhibitors of AβPP dimerization, and identified a compound that reduces Aβ levels. In the present study, we have identified an analog, compound Y10, which also reduced Aβ. Initial kinase profiling assays identified the receptor tyrosine kinase cKit as a putative Y10 target. To elucidate the precise mechanism involved, AβPP phosphorylation was examined by IP-western blotting. We found that Y10 inhibits cKit phosphorylation and increases AβPP phosphorylation mainly on tyrosine residue Y743, according to AβPP751 numbering. A known cKit inhibitor and siRNA specific to cKit were also found to increase AβPP phosphorylation and lower Aβ levels. We also investigated a cKit downstream signaling molecule, the Shp2 phosphatase, and found that known Shp2 inhibitors and siRNA specific to Shp2 also increase AβPP phosphorylation, suggesting that the cKit signaling pathway is also involved in AβPP phosphorylation and Aβ production. We further found that inhibitors of both cKit and Shp2 enhance AβPP surface localization. Thus, regulation of AβPP phosphorylation by small molecules should be considered as a novel therapeutic intervention for AD.

KEYWORDS:

High throughput screening; kinase; neurodegeneration; phosphatase; phosphorylation

PMID:
30776010
DOI:
10.3233/JAD-180923

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