title: Niemann-Pick type C cells show cholesterol dependent decrease of APP expression at the cell surface and its increased processing through the beta-secretase pathway.
abstract: The link between cholesterol and Alzheimer's disease has recently been revealed in Niemann-Pick type C disease. We found that NPC1(-/-) cells show decreased expression of APP at the cell surface and increased processing of APP through the beta-secretase pathway resulting in increased C99, sAPPbeta and intracellular Abeta40 levels. This effect is dependent on increased cholesterol levels, since cholesterol depletion reversed cell surface APP expression and lowered Abeta/C99 levels in NPC1(-)(/)(-) cells to the levels observed in wt cells. Finding that overexpression of C99, a direct gamma-secretase substrate, does not lead to increased intracellular Abeta levels in NPC1(-)(/)(-) cells vs. CHOwt suggests that the effect on intracellular Abeta upon cholesterol accumulation in NPC1(-)(/)(-) cells is not due to increased APP cleavage by gamma-secretase. Our results indicate that cholesterol may modulate APP processing indirectly by modulating APP expression at the cell surface and thus its cleavage by beta-secretase.
authors.affiliation: Division of Molecular Medicine, Rudjer Boskovic Institute, 10000 Zagreb, Croatia.
authors.forename: Martina
authors.initials: M
authors.lastname: Malnar
authors.forename: Marko
authors.initials: M
authors.lastname: Kosicek
authors.forename: Stefan
authors.initials: S
authors.lastname: Mitterreiter
authors.forename: Damir
authors.initials: D
authors.lastname: Omerbasic
authors.forename: Stefan F
authors.initials: SF
authors.lastname: Lichtenthaler
authors.forename: Alison
authors.initials: A
authors.lastname: Goate
authors.forename: Silva
authors.initials: S
authors.lastname: Hecimovic
mesh_terms: D053829:Amyloid Precursor Protein Secretases / Q000378:metabolism*; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism; D016466:CHO Cells; D002352:Carrier Proteins / Q000235:genetics* / Q000502:physiology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism / Q000494:pharmacology*; D006224:Cricetinae; D003412:Cricetulus; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000502:physiology; D000077296:Niemann-Pick C1 Protein; D052556:Niemann-Pick Disease, Type C / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014162:Transfection
chemical_list: D016564:Amyloid beta-Protein Precursor; D000954:Antigens, Surface; D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; C106881:NPC1 protein, human; D000077296:Niemann-Pick C1 Protein; D002784:Cholesterol; D053829:Amyloid Precursor Protein Secretases