Amyloid β-peptide (Aβ) is generated by the consecutive cleavages of β- and γ-secretase. The intramembraneous γ-secretase cleavage critically depends on the activity of presenilins (PS1 and PS2). Although there is evidence that PSs are aspartyl proteases with γ-secretase activity, it remains controversial whether their subcellular localization overlaps with the cellular sites of Aβ production. We now demonstrate that biologically active GFP-tagged PS1 as well as endogenous PS1 are targeted to the plasma membrane (PM) of living cells. On the way to the PM, PS1 binds to nicastrin (Nct), an essential component of the γ-secretase complex. This complex is targeted through the secretory pathway where PS1-bound Nct becomes endoglycosidase H resistant. Moreover, surface-biotinylated Nct can be coimmunoprecipitated with PS1 antibodies, demonstrating that this complex is located to cellular sites with γ-secretase activity. Inactivating PS1 or PS2 function by mutagenesis of one of the critical aspartate residues or by γ-secretase inhibitors results in delayed reinternalization of the β-amyloid precursor protein and its accumulation at the cell surface. Our data suggest that PS is targeted as a biologically active complex with Nct through the secretory pathway to the cell surface and suggest a dual function of PS in γ-secretase processing and in trafficking.
Presenilin-1 affects trafficking and processing of βAPP and is targeted in a complex with nicastrin to the plasma membrane
The online version of this article includes supplemental material.
Abbreviations used in this paper: Aβ, amyloid β-peptide; Aβ42, 42–amino acid amyloid β-peptide; BACE, β-site APP cleaving enzyme; βAPP, β-amyloid precursor protein; CTF, COOH-terminal fragment; EEA1, early endosomal autoantigen 1; endoH, endoglycosidase H; FAD, familial Alzheimer's disease; GSK-3, glycogen synthase kinase 3; HEK, human embryonic kidney; Nct, nicastrin; NICD, Notch intracellular domain; NTF, NH2-terminal fragment; PE, PS1–EGFP; PEASP, PS1 D385N–EGFP; PM, plasma membrane; PS, presenilin; TIRM, total internal reflection microscopy; wt, wild type.
Christoph Kaether, Sven Lammich, Dieter Edbauer, Michaela Ertl, Jens Rietdorf, Anja Capell, Harald Steiner, Christian Haass; Presenilin-1 affects trafficking and processing of βAPP and is targeted in a complex with nicastrin to the plasma membrane . J Cell Biol 5 August 2002; 158 (3): 551–561. doi: https://doi.org/10.1083/jcb.200201123
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