title: Familial Alzheimer disease-linked presenilin 1 variants enhance production of both Abeta 1-40 and Abeta 1-42 peptides that are only partially sensitive to a potent aspartyl protease transition state inhibitor of "gamma-secretase".
abstract: Presenilin 1 (PS1) plays an essential role in intramembranous "gamma-secretase" processing of several type I membrane proteins, including the beta-amyloid precursor proteins (APP) and Notch1. In this report, we examine the activity of two familial Alzheimer's disease-linked PS1 variants on the production of secreted Abeta peptides and the effects of L-685,458, a potent gamma-secretase inhibitor, on inhibition of Abeta peptides from cells expressing these PS1 variants. We now report that PS1 variants enhance the production and secretion of both Abeta1-42 and Abeta1-40 peptides. More surprisingly, whereas the IC(50) for inhibition of Abeta1-40 peptide production from cells expressing wild-type PS1 is approximately 1.5 microm, cells expressing the PS1deltaE9 mutant PS1 exhibit an IC(50) of approximately 4 microm. Immunoprecipitation and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry reveal that the levels of Abeta1-43 peptides are elevated in medium of PS1deltaE9 cells treated with higher concentrations of inhibitor. The differential effects of wild-type and mutant PS1 on gamma-secretase production of Abeta peptides and the disparity in sensitivity of these peptides to a potent gamma-secretase suggest that PS may be necessary, but not sufficient, to catalyze hydrolysis at the scissile bonds that generate the termini of Abeta1-40 and Abeta1-42 peptides.
authors.affiliation: Department of Neurobiology, Pharmacology and Physiology, The University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ikeuchi
authors.forename: Georgia
authors.initials: G
authors.lastname: Dolios
authors.forename: Seong-Hun
authors.initials: SH
authors.lastname: Kim
authors.forename: Rong
authors.initials: R
authors.lastname: Wang
authors.forename: Sangram S
authors.initials: SS
authors.lastname: Sisodia
mesh_terms: D053829:Amyloid Precursor Protein Secretases; D016229:Amyloid beta-Peptides / Q000096:biosynthesis*; D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006868:Hydrolysis; D015151:Immunoblotting; D020128:Inhibitory Concentration 50; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000235:genetics* / Q000502:physiology*; D051379:Mice; D010446:Peptide Fragments / Q000096:biosynthesis*; D010455:Peptides / Q000737:chemistry; D011233:Precipitin Tests; D053764:Presenilin-1; D017434:Protein Structure, Tertiary; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014407:Tumor Cells, Cultured
chemical_list: D016229:Amyloid beta-Peptides; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D010446:Peptide Fragments; D010455:Peptides; D053764:Presenilin-1; C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42); D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509282:Bace1 protein, mouse