title: Binding of cystatin C to Alzheimer's amyloid beta inhibits in vitro amyloid fibril formation.
abstract: The colocalization of cystatin C, an inhibitor of cysteine proteases, with amyloid beta (Abeta) in parenchymal and vascular amyloid deposits in brains of Alzheimer's disease (AD) patients may reflect cystatin C involvement in amyloidogenesis. We therefore sought to determine the association of cystatin C with Abeta. Immunofluorescence analysis of transfected cultured cells demonstrated colocalization of cystatin C and beta amyloid precursor protein (betaAPP) intracellularly and on the cell surface. Western blot analysis of immunoprecipitated cell lysate or medium proteins revealed binding of cystatin C to full-length betaAPP and to secreted betaAPP (sbetaAPP). Deletion mutants of betaAPP localized the cystatin C binding site within betaAPP to the Abeta region. Cystatin C association with betaAPP resulted in increased sbetaAPP but did not affect levels of secreted Abeta. Analysis of the association of cystatin C and Abeta demonstrated a specific, saturable and high affinity binding between cystatin C and both Abeta(1-42) and Abeta(1-40). Notably, cystatin C association with Abeta results in a concentration-dependent inhibition of Abeta fibril formation.
authors.affiliation: Departments of Pharmacology, New York University School of Medicine, 550 First Avenue, New York, NY, 10016, USA.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Sastre
authors.forename: Miguel
authors.initials: M
authors.lastname: Calero
authors.forename: Monika
authors.initials: M
authors.lastname: Pawlik
authors.forename: Paul M
authors.initials: PM
authors.lastname: Mathews
authors.forename: Asok
authors.initials: A
authors.lastname: Kumar
authors.forename: Vlatko
authors.initials: V
authors.lastname: Danilov
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Schmidt
authors.forename: Ralph A
authors.initials: RA
authors.lastname: Nixon
authors.forename: Blas
authors.initials: B
authors.lastname: Frangione
authors.forename: Efrat
authors.initials: E
authors.lastname: Levy
mesh_terms: D000544:Alzheimer Disease / Q000188:drug therapy / Q000378:metabolism* / Q000503:physiopathology; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D016564:Amyloid beta-Protein Precursor / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D001921:Brain / Q000378:metabolism* / Q000503:physiopathology; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D055316:Cystatin C; D015891:Cystatins / Q000235:genetics / Q000378:metabolism*; D003546:Cysteine Endopeptidases / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006801:Humans; D051379:Mice; D009154:Mutation / Q000235:genetics; D010446:Peptide Fragments / Q000378:metabolism; D058225:Plaque, Amyloid / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000378:metabolism
chemical_list: D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; C525030:CST3 protein, human; C525031:Cst3 protein, mouse; D055316:Cystatin C; D015891:Cystatins; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42); D003546:Cysteine Endopeptidases