Cyclic cis-Locked Phospho-Dipeptides Reduce Entry of AβPP into Amyloidogenic Processing Pathway.

Abstract

The cis/trans isomerization of X-Pro peptide bonds in proteins in some instances acts as a molecular switch in biological pathways. Our prior work suggests that the cis isomer of the phospho-Thr668-Pro669 motif, located in the cytoplasmic domain of the amyloid-β protein precursor (AβPP), is correlated with an increase in amyloidogenic processing of AβPP and production of amyloid-beta (Aβ), the neurotoxic peptide fragment in Alzheimer's disease (AD). We designed a 100% cis-locked cyclic dipeptide composed of cyclized phospho-Thr-Pro (pCDP) as a mimic for this putative pathological conformation, and three phosphate-blocked derivatives (pCDP-diBzl, pCDP-Bzl, and pCDP-diPOM). Two H4 neuroglioma cell lines were established as AD cell models for use in testing these compounds: H4-AβPP695 for stable overexpression of wild-type AβPP695, and H4-BACE1 for stable overexpression of β-site AβPP cleaving enzyme-1 (BACE1). The level of the secreted AβPP fragment resulting from BACE1 activity, sAβPPβ, served as a key proxy for amyloidogenic processing, since cleavage of AβPP by BACE1 is a requisite first step in Aβ production. Of the compounds tested, pCDP-diBzl decreased sAβPPβ levels in both cell lines, while pCDP-diPOM decreased sAβPPβ levels in only H4-BACE1 cells, all with similar dose-dependences and patterns of proteolytic AβPP fragments. Enzymatic assays showed that none of the pCDP derivatives directly inhibit BACE1 catalytic activity. These results suggest a model in which pCDP-diBzl and pCDP-diPOM act at a common point to inhibit entry of AβPP into the amyloidogenic AβPP processing pathway but through different targets, and provide important insights for the development of novel AD therapeutics.

DOI: 10.3233/JAD-160051

8 Figures and Tables

Statistics

05002017
Citations per Year

78 Citations

Semantic Scholar estimates that this publication has 78 citations based on the available data.

See our FAQ for additional information.

Cite this paper

@article{Fisher2017CyclicCP, title={Cyclic cis-Locked Phospho-Dipeptides Reduce Entry of AβPP into Amyloidogenic Processing Pathway.}, author={Carolyn L Fisher and Ross J Resnick and Soumya De and Lucila Andrea Acevedo and Kun Lu and Frank C Schroeder and Linda K Nicholson}, journal={Journal of Alzheimer's disease : JAD}, year={2017}, volume={55 1}, pages={391-410} }