title: Catalytic site-directed gamma-secretase complex inhibitors do not discriminate pharmacologically between Notch S3 and beta-APP cleavages.
abstract: The generation of gamma-secretase inhibitors which block the release of beta-amyloid peptide (Abeta) has long been an attractive therapeutic avenue for treatment or prevention of Alzheimer's disease (AD). Such inhibitors would reduce levels of Abeta available for aggregation into toxic assemblies that lead to the plaque pathology found in affected brain tissue. Cumulative evidence suggests that the S3 cleavage of Notch is also dependent on presenilins (PS) and is carried out by the multimeric PS-containing gamma-secretase complex. It is therefore possible that Notch function could be affected by gamma-secretase inhibitors. To assess the relationship between the cleavage of these substrates in the same system, Western blot cleavage assays have been established using a human cell line stably expressing both the beta-amyloid precursor protein (beta-APP) and the truncated Notch1 receptor fragment NotchDeltaE. Thus, a direct correlation may be made, following inhibitor treatment, of the decrease in the levels of the cleavage products, Abeta peptide and the Notch intracellular domain (NICD), as well as the increase in stabilized levels of both substrates. This analysis has been performed with a range of selected gamma-secretase inhibitors from six distinct structural classes. Changes in all four species usually occur in concert and with remarkably good agreement. A significant cleavage window is not clearly apparent in any case. Thus, these Notch and beta-APP cleavages cannot be dissected apart easily since they show the same pharmacological profile of inhibition. Whether this translates into proportionally reduced Notch signaling in vivo, however, remains to be seen.
authors.affiliation: Department of Biochemistry and Molecular Biology, The Neuroscience Research Centre, Merck Sharp & Dohme Research Laboratories, Terlings Park, Harlow, Essex, UK.
authors.forename: Huw D
authors.initials: HD
authors.lastname: Lewis
authors.forename: Blanca I
authors.initials: BI
authors.lastname: Pérez Revuelta
authors.forename: Alan
authors.initials: A
authors.lastname: Nadin
authors.forename: Joe G
authors.initials: JG
authors.lastname: Neduvelil
authors.forename: Timothy
authors.initials: T
authors.lastname: Harrison
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Pollack
authors.forename: Mark S
authors.initials: MS
authors.lastname: Shearman
mesh_terms: D000544:Alzheimer Disease / Q000201:enzymology; D053829:Amyloid Precursor Protein Secretases; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D016282:Aspartic Acid Endopeptidases; D015153:Blotting, Western; D002219:Carbamates / Q000032:analysis / Q000737:chemistry; D020134:Catalytic Domain; D002460:Cell Line; D004151:Dipeptides / Q000032:analysis / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D010450:Endopeptidases / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D020128:Inhibitory Concentration 50; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D018716:Molecular Mimicry; D011480:Protease Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D017434:Protein Structure, Tertiary; D051880:Receptors, Notch; D015398:Signal Transduction
chemical_list: D016564:Amyloid beta-Protein Precursor; D002219:Carbamates; D004151:Dipeptides; C410009:L 685458; D008565:Membrane Proteins; D011480:Protease Inhibitors; D051880:Receptors, Notch; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human