title: Insensitivity to Abeta42-lowering nonsteroidal anti-inflammatory drugs and gamma-secretase inhibitors is common among aggressive presenilin-1 mutations.
abstract: Abeta42-lowering nonsteroidal anti-inflammatory drugs (NSAIDs) constitute the founding members of a new class of gamma-secretase modulators that avoid side effects of pan-gamma-secretase inhibitors on NOTCH processing and function, holding promise as potential disease-modifying agents for Alzheimer disease (AD). These modulators are active in cell-free gamma-secretase assays indicating that they directly target the gamma-secretase complex. Additional support for this hypothesis was provided by the observation that certain mutations in presenilin-1 (PS1) associated with early-onset familial AD (FAD) change the cellular drug response to Abeta42-lowering NSAIDs. Of particular interest is the PS1-DeltaExon9 mutation, which provokes a pathogenic increase in the Abeta42/Abeta40 ratio and dramatically reduces the cellular response to the Abeta42-lowering NSAID sulindac sulfide. This FAD PS1 mutant is unusual as a splice-site mutation results in deletion of amino acids Thr(291)-Ser(319) including the endoproteolytic cleavage site of PS1, and an additional amino acid exchange (S290C) at the exon 8/10 splice junction. By genetic dissection of the PS1-DeltaExon9 mutation, we now demonstrate that a synergistic effect of the S290C mutation and the lack of endoproteolytic cleavage is sufficient to elevate the Abeta42/Abeta40 ratio and that the attenuated response to sulindac sulfide results partially from the deficiency in endoproteolysis. Importantly, a wider screen revealed that a diminished response to Abeta42-lowering NSAIDs is common among aggressive FAD PS1 mutations. Surprisingly, these mutations were also partially unresponsive to gamma-secretase inhibitors of different structural classes. This was confirmed in a mouse model with transgenic expression of the PS1-L166P mutation, in which the potent gamma-secretase inhibitor LY-411575 failed to reduce brain levels of soluble Abeta42. In summary, these findings highlight the importance of genetic background in drug discovery efforts aimed at gamma-secretase, suggesting that certain AD mouse models harboring aggressive PS mutations may not be informative in assessing in vivo effects of gamma-secretase modulators and inhibitors.
authors.affiliation: Emmy Noether Research Group, Mainz, Germany.
authors.forename: Eva
authors.initials: E
authors.lastname: Czirr
authors.forename: Stefanie
authors.initials: S
authors.lastname: Leuchtenberger
authors.forename: Cornelia
authors.initials: C
authors.lastname: Dorner-Ciossek
authors.forename: Anna
authors.initials: A
authors.lastname: Schneider
authors.forename: Mathias
authors.initials: M
authors.lastname: Jucker
authors.forename: Edward H
authors.initials: EH
authors.lastname: Koo
authors.forename: Claus U
authors.initials: CU
authors.lastname: Pietrzik
authors.forename: Karlheinz
authors.initials: K
authors.lastname: Baumann
authors.forename: Sascha
authors.initials: S
authors.lastname: Weggen
mesh_terms: D000544:Alzheimer Disease / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D053829:Amyloid Precursor Protein Secretases / Q000037:antagonists & inhibitors*; D016229:Amyloid beta-Peptides / Q000378:metabolism* / Q000502:physiology*; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D009154:Mutation; D010446:Peptide Fragments / Q000378:metabolism* / Q000502:physiology*; D053764:Presenilin-1 / Q000235:genetics* / Q000502:physiology*; D017386:Sequence Homology, Amino Acid
chemical_list: D016229:Amyloid beta-Peptides; D000894:Anti-Inflammatory Agents, Non-Steroidal; D004791:Enzyme Inhibitors; D010446:Peptide Fragments; D053764:Presenilin-1; C075222:amyloid beta-protein (1-42); D053829:Amyloid Precursor Protein Secretases