title: Pharmacological knock-down of the presenilin 1 heterodimer by a novel gamma -secretase inhibitor: implications for presenilin biology.
abstract: Intramembranous cleavage of the beta-amyloid precursor protein by gamma-secretase is the final processing event generating amyloid-beta peptides, which are thought to be causative agents for Alzheimer's disease. Missense mutations in the presenilin genes co-segregate with early-onset Alzheimer's disease, and, recently, a close biochemical linkage between presenilins and the identity of gamma-secretase has been established. Here we describe for the first time that certain potent gamma-secretase inhibitors are able to interfere with the endoproteolytic processing of presenilin 1 (PS1). In addition, we identified a novel gamma-secretase inhibitor, [1S-benzyl-4R-[1-(5-cyclohexyl-2-oxo-2,3-dihydro-1H-benzo[e][1,4]diazepin-3(R,S)-ylcarbamoyl)-S-ethylcarbamoyl]-2R-hydroxy-5-phenyl-pentyl]-carbamic acid tert-butyl ester (CBAP), which not only physically interacts with PS1, but upon chronic treatment produces a "pharmacological knock-down" of PS1 fragments. This indicates that the observed accumulation of full-length PS1 is caused by a direct inhibition of its endoproteolysis. The subsequent use of CBAP as a biological tool to increase full-length PS1 levels in the absence of exogenous PS1 expression has provided evidence that wild-type PS1 endoproteolysis is not required either for PS1/gamma-secretase complex assembly or trafficking. Furthermore, in cell-based systems CBAP does not completely recapitulate PS1 loss-of-function phenotypes. Even though the beta-amyloid precursor protein cleavage and the S3 cleavage of the Notch receptor are inhibited by CBAP, an impairment of Trk receptor maturation was not observed.
authors.affiliation: Department of Biochemistry & Molecular Biology, Merck Sharp & Dohme Research Laboratories, The Neuroscience Research Centre, Terlings Park, Harlow, Essex CM20 2QR, United Kingdom. dirk_beher@merck.com
authors.forename: D
authors.initials: D
authors.lastname: Beher
authors.forename: J D
authors.initials: JD
authors.lastname: Wrigley
authors.forename: A
authors.initials: A
authors.lastname: Nadin
authors.forename: G
authors.initials: G
authors.lastname: Evin
authors.forename: C L
authors.initials: CL
authors.lastname: Masters
authors.forename: T
authors.initials: T
authors.lastname: Harrison
authors.forename: J L
authors.initials: JL
authors.lastname: Castro
authors.forename: M S
authors.initials: MS
authors.lastname: Shearman
mesh_terms: D053829:Amyloid Precursor Protein Secretases; D000818:Animals; D016282:Aspartic Acid Endopeptidases; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002498:Centrifugation; D018076:DNA, Complementary / Q000378:metabolism; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D010450:Endopeptidases / Q000737:chemistry* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D020128:Inhibitory Concentration 50; D007700:Kinetics; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D020125:Mutation, Missense; D010641:Phenotype; D053764:Presenilin-1; D011485:Protein Binding; D051381:Rats; D013329:Structure-Activity Relationship; D013347:Subcellular Fractions; D013997:Time Factors; D014162:Transfection; D014407:Tumor Cells, Cultured; D014466:Ultraviolet Rays
chemical_list: D018076:DNA, Complementary; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; C508853:PSEN1 protein, human; D053764:Presenilin-1; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human