Binding of cystatin C to Alzheimer's amyloid beta inhibits in vitro amyloid fibril formation.
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.
Sastre
Magdalena
M
Departments of Pharmacology, New York University School of Medicine, 550 First Avenue, New York, NY, 10016, USA.
Calero
Miguel
M
Pawlik
Monika
M
Mathews
Paul M
PM
Kumar
Asok
A
Danilov
Vlatko
V
Schmidt
Stephen D
SD
Nixon
Ralph A
RA
Frangione
Blas
B
Levy
Efrat
E
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
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