title: Generation of amyloid-β is reduced by the interaction of calreticulin with amyloid precursor protein, presenilin and nicastrin.
abstract: Dysregulation of the proteolytic processing of amyloid precursor protein by γ-secretase and the ensuing generation of amyloid-β is associated with the pathogenesis of Alzheimer's disease. Thus, the identification of amyloid precursor protein binding proteins involved in regulating processing of amyloid precursor protein by the γ-secretase complex is essential for understanding the mechanisms underlying the molecular pathology of the disease. We identified calreticulin as novel amyloid precursor protein interaction partner that binds to the γ-secretase cleavage site within amyloid precursor protein and showed that this Ca(2+)- and N-glycan-independent interaction is mediated by amino acids 330-344 in the C-terminal C-domain of calreticulin. Co-immunoprecipitation confirmed that calreticulin is not only associated with amyloid precursor protein but also with the γ-secretase complex members presenilin and nicastrin. Calreticulin was detected at the cell surface by surface biotinylation of cells overexpressing amyloid precursor protein and was co-localized by immunostaining with amyloid precursor protein and presenilin at the cell surface of hippocampal neurons. The P-domain of calreticulin located between the N-terminal N-domain and the C-domain interacts with presenilin, the catalytic subunit of the γ-secretase complex. The P- and C-domains also interact with nicastrin, another functionally important subunit of this complex. Transfection of amyloid precursor protein overexpressing cells with full-length calreticulin leads to a decrease in amyloid-β42 levels in culture supernatants, while transfection with the P-domain increases amyloid-β40 levels. Similarly, application of the recombinant P- or C-domains and of a synthetic calreticulin peptide comprising amino acid 330-344 to amyloid precursor protein overexpressing cells result in elevated amyloid-β40 and amyloid-β42 levels, respectively. These findings indicate that the interaction of calreticulin with amyloid precursor protein and the γ-secretase complex regulates the proteolytic processing of amyloid precursor protein by the γ-secretase complex, pointing to calreticulin as a potential target for therapy in Alzheimer's disease.
authors.affiliation: Zentrum für Molekulare Neurobiologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Nina
authors.initials: N
authors.lastname: Stemmer
authors.forename: Elena
authors.initials: E
authors.lastname: Strekalova
authors.forename: Nevena
authors.initials: N
authors.lastname: Djogo
authors.forename: Frank
authors.initials: F
authors.lastname: Plöger
authors.forename: Gabriele
authors.initials: G
authors.lastname: Loers
authors.forename: David
authors.initials: D
authors.lastname: Lutz
authors.forename: Friedrich
authors.initials: F
authors.lastname: Buck
authors.forename: Marek
authors.initials: M
authors.lastname: Michalak
authors.forename: Melitta
authors.initials: M
authors.lastname: Schachner
authors.forename: Ralf
authors.initials: R
authors.lastname: Kleene
mesh_terms: D000595:Amino Acid Sequence; D053829:Amyloid Precursor Protein Secretases / Q000235:genetics* / Q000378:metabolism; D016229:Amyloid beta-Peptides / Q000378:metabolism; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D006224:Cricetinae; D005786:Gene Expression Regulation; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D053764:Presenilin-1 / Q000235:genetics* / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D059748:Proteolysis; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D008562:Membrane Glycoproteins; C508853:PSEN1 protein, human; D010446:Peptide Fragments; D053764:Presenilin-1; D011994:Recombinant Proteins; C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42); C413604:nicastrin protein; D053829:Amyloid Precursor Protein Secretases