Charles Sanders
Faculty Member
Last active: 3/3/2020

Bexarotene Binds to the Amyloid Precursor Protein Transmembrane Domain, Alters Its α-Helical Conformation, and Inhibits γ-Secretase Nonselectively in Liposomes.

Kamp F, Scheidt HA, Winkler E, Basset G, Heinel H, Hutchison JM, LaPointe LM, Sanders CR, Steiner H, Huster D
ACS Chem Neurosci. 2018 9 (7): 1702-1713

PMID: 29717863 · PMCID: PMC6051911 · DOI:10.1021/acschemneuro.8b00068

Bexarotene is a pleiotropic molecule that has been proposed as an amyloid-β (Aβ)-lowering drug for the treatment of Alzheimer's disease (AD). It acts by upregulation of an apolipoprotein E (apoE)-mediated Aβ clearance mechanism. However, whether bexarotene induces removal of Aβ plaques in mouse models of AD has been controversial. Here, we show by NMR and CD spectroscopy that bexarotene directly interacts with and stabilizes the transmembrane domain α-helix of the amyloid precursor protein (APP) in a region where cholesterol binds. This effect is not mediated by changes in membrane lipid packing, as bexarotene does not share with cholesterol the property of inducing phospholipid condensation. Bexarotene inhibited the intramembrane cleavage by γ-secretase of the APP C-terminal fragment C99 to release Aβ in cell-free assays of the reconstituted enzyme in liposomes, but not in cells, and only at very high micromolar concentrations. Surprisingly, in vitro, bexarotene also inhibited the cleavage of Notch1, another major γ-secretase substrate, demonstrating that its inhibition of γ-secretase is not substrate specific and not mediated by acting via the cholesterol binding site of C99. Our data suggest that bexarotene is a pleiotropic molecule that interfere with Aβ metabolism through multiple mechanisms.

MeSH Terms (14)

Amyloid beta-Protein Precursor Amyloid Precursor Protein Secretases Bexarotene Cholesterol HEK293 Cells Humans Liposomes Molecular Structure Neuroprotective Agents Phosphatidylcholines Protein Conformation, alpha-Helical Protein Domains Receptor, Notch1 Static Electricity

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