Analysis by a highly sensitive split luciferase assay of the regions involved in APP dimerization and its impact on processing. Issue 1 (6th September 2015)

• Record Type: Journal Article
• Authors: Decock, Marie; El Haylani, Laetitia; Stanga, Serena; Dewachter, Ilse; Octave, Jean-Noël; Smith, Steven O.; Constantinescu, Stefan N.; Kienlen-Campard, Pascal
• Is Part Of: FEBS open bio. Volume 5:Issue 1(2015)
• Page Start: 763
• Page End: 773
• Publication Date: 2015-09-06
• Subjects: Aβ -- β-amyloid peptide -- AD -- Alzheimer's disease -- APP -- amyloid precursor protein -- AICD -- APP intracellular domain -- sAPPα -- soluble APPα -- sAPPβ -- soluble APPβ -- CHO -- chinese hamster ovary -- CTF -- C-terminal fragment -- DAPT -- N-[N-(3, 5-difluorophenacetyl)-l-alanyl]-S-phenylglycinet-butyl ester -- DTT -- dithiothreitol -- ECL -- enzymatic chemi-luminescence -- ECLIA -- electro-chemiluminescence immuno-assay -- FBS -- fetal bovine serum -- FRET -- fluorescence resonance energy transfer -- KPI -- Kunitz-type protease inhibitor -- NSAIDs -- nonsteroidal anti-inflammatory drugs -- PBS -- phosphate buffered saline -- PS1/PS2 -- presenilin1/presenilin2 -- RLU -- relative light unit -- SP -- signal peptide -- TM -- transmembrane -- YFP -- yellow fluorescent protein -- Alzheimer disease -- APP -- Dimerization -- GXXXG motifs -- Amyloid beta peptide -- Split luciferase; Molecular biology -- Periodicals; Cytology -- Periodicals; Life sciences -- Periodicals; Biological Science Disciplines -- Periodicals; Molecular Biology -- Periodicals; Cell Biology -- Periodicals; Cytology; Life sciences; Molecular biology; Periodicals; 572.805
• DOI: 10.1016/j.fob.2015.09.002
• Languages: English
• ISSNs: 2211-5463

Abstract

Abstract : Alzheimer's disease (AD) is a neurodegenerative disease that causes progressive loss of cognitive functions, leading to dementia. Two types of lesions are found in AD brains: neurofibrillary tangles and senile plaques. The latter are composed mainly of the β‐amyloid peptide (Aβ) generated by amyloidogenic processing of the amyloid precursor protein (APP). Several studies have suggested that dimerization of APP is closely linked to Aβ production. Nevertheless, the mechanisms controlling APP dimerization and their role in APP function are not known. Here we used a new luciferase complementation assay to analyze APP dimerization and unravel the involvement of its three major domains: the ectodomain, the transmembrane domain and the intracellular domain. Our results indicate that within cells full‐length APP dimerizes more than its α and β C‐terminal fragments, confirming the pivotal role of the ectodomain in this process. Dimerization of the APP transmembrane (TM) domain has been reported to regulate processing at the γ‐cleavage site. We show that both non‐familial and familial AD mutations in the TM GXXXG motifs strongly modulate Aβ production, but do not consistently change dimerization of the C‐terminal fragments. Finally, we found for the first time that removal of intracellular domain strongly increases APP dimerization. Increased APP dimerization is linked to increased non‐amyloidogenic processing. Abstract : Amyloid precursor protein (APP) dimerizes more than its C‐terminal fragments in cells. Mutations of membrane GXXXG motifs affect Aβ production but not APP dimerization. Deletion of the APP intracellular domain increases APP dimerization.