Wild-type but not Alzheimer-mutant amyloid precursor protein confers resistance against p53-mediated apoptosis

Abstract

Amyloid precursor proteins (APPs) are expressed in multiple organs and cell types in diverse species. Their conservation across species and high abundance in brain and the association of various APP missense mutations with autosomal dominant forms of familial Alzheimer's disease (FAD) suggest important roles for APP in the central nervous system. However, the basic functions of APP in the central nervous system remain largely unknown. To assess potential effects of APP on neuronal death and survival, we transfected APP-deficient rat neuroblastoma cells (B103) with DNA constructs encoding wild-type or FAD-mutant human APP. Wild-type, but not FAD-mutant, APP effectively protected cells against apoptosis induced by ultraviolet irradiation, staurosporine, or p53. Wild-type APP also strongly inhibited p53 DNA-binding activity and p53-mediated gene transactivation, whereas FAD-mutant APP did not. We conclude that APP protects neuronal cells against apoptosis by controlling p53 activation at the post-translational level. Disruption of this function by mutations or alterations in APP processing could enhance neuronal vulnerability to secondary insults and contribute to neuronal degeneration.

Amyloid precursor protein and amyloid β-peptide bind to ATP synthase and regulate its activity at the surface of neural cells

“…26 CHL1-Fc and PrP-Fc that contain the extracellular domain of these adhesion molecules in fusion with Fc were expressed and, as for the APPFc fusion proteins, purified via the Fc-tag using a Protein-A column chromatography as described. 26 Cell culture B103 cells that do not express APP 27 were stably transfected with pcDNA 3.1(À) containing the human cDNA sequence of APP 695, the predominantly neuronal expressed isoform of APP. 3 Cells were maintained in Dulbecco's modified Eagle's medium containing 10% fetal bovine serum and 5% horse serum supplemented with hygromycin for selection.…”

Bioluminescence imaging of Smad signaling in living mice shows correlation with excitotoxic neurodegeneration

“…To differentiate Neuro-2a cells, cells were maintained in Neurobasal media with 2 mM glutamine and 1ϫ N2 supplement (Invitrogen). Rat neuroblastoma cells B103 stably expressing wild-type human amyloid precursor protein and neomycin resistance gene (47) were cultured in DMEM with 2 mM glutamine and 10% FBS. Neuro-2a and B103 cells were transfected with the following plasmids: CMV-Flag-Smad2 (0.3 g per well), CMV-Flag-Smad3 (0.3 g per well), and CMVFlag-Smad4 (0.1 g per well; a kind gift from Rik Derynck, University of California, San Francisco, CA).…”

The role of p53 in neuronal cell death

“…Wild-type human APP was shown to prevent cell death in a differentiated neuronal cell line in response to elevated p53 expression induced by UV irradiation, staurosporine treatment and p53-adenovirus infection. 111 Mutant forms of APP associated with familial-early onset forms of Alzheimer's disease did not confer protection. While neither form of APP altered p53 protein levels or p53 nuclear translocation, wild-type APP, in contrast to mutant APP, suppressed p53-mediated transcriptional activation from a p53-responsive promoter.…”