Document Detail


Calpain activity regulates the cell surface distribution of amyloid precursor protein. Inhibition of calpains enhances endosomal generation of beta-cleaved C-terminal APP fragments.
MedLine Citation:
PMID:  12087104     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
In murine L cells, treatment with calpeptin or calpain inhibitor III increased Abeta42, but not Abeta40, secretion in a dose-dependent fashion. This correlated with an increase in the levels of amyloid precursor protein (APP) carboxyl-terminal fragments (CTFs). Immunoprecipitation with novel mAbs directed against the carboxyl-terminus of APP or specific for the beta-cleaved CTF showed that generation of both alpha- and beta-cleaved CTFs increase proportionately following inhibition of calpains. Pulse-chase metabolic labeling confirmed that inhibiting calpains increases the production of alpha- and beta-cleaved APP metabolites. Immunolabeling showed greater betaCTF signal in calpeptin-treated cells, primarily in small vesicular compartments that were shown to be predominantly endosomal by colocalization with early endosomal antigen 1. A second mAb, which recognizes an extracellular/luminal epitope found on both APP and betaCTFs, gave more cell surface labeling of calpeptin-treated cells than control cells. Quantitative binding of this antibody confirmed that inhibiting calpains caused a partial redistribution of APP to the cell surface. These results demonstrate that 1) calpain inhibition results in a partial redistribution of APP to the cell surface, 2) this redistribution leads to an increase in both alpha- and beta-cleavage without changing the ratio of alphaCTFs/betaCTFs, and 3) the bulk of the betaCTFs in the cell are within early endosomes, confirming the importance of this compartment in APP processing.
Authors:
Paul M Mathews; Ying Jiang; Stephen D Schmidt; Olivera M Grbovic; Marc Mercken; Ralph A Nixon
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.     Date:  2002-06-26
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  277     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  2002 Sep 
Date Detail:
Created Date:  2002-09-23     Completed Date:  2002-11-13     Revised Date:  2008-09-28    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  36415-24     Citation Subset:  IM    
Affiliation:
Nathan Kline Institute, Orangeburg, New York 10962, USA. mathews@nki.rfmh.org
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MeSH Terms
Descriptor/Qualifier:
Amyloid beta-Protein Precursor / metabolism*
Animals
Antibodies, Monoclonal / metabolism
Blotting, Western
Calpain / antagonists & inhibitors,  metabolism*
Cell Line
Cell Membrane / metabolism*
Dipeptides / antagonists & inhibitors,  metabolism
Dose-Response Relationship, Drug
Endosomes / metabolism
Enzyme-Linked Immunosorbent Assay
Humans
Hydrogen-Ion Concentration
Mice
Microscopy, Confocal
Microscopy, Fluorescence
Models, Genetic
Mutation
Precipitin Tests
Protein Binding
Protein Structure, Tertiary
Time Factors
Tumor Cells, Cultured
Chemical
Reg. No./Substance:
0/Amyloid beta-Protein Precursor; 0/Antibodies, Monoclonal; 0/Dipeptides; 117591-20-5/calpeptin; EC 3.4.22.-/Calpain

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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