title: Characterization of the signaling pathway downstream p75 neurotrophin receptor involved in beta-amyloid peptide-dependent cell death.
abstract: The accumulation of beta-amyloid (Abeta) peptide is a key pathogenic event in Alzheimer's disease. Previous studies have shown that Abeta peptide can damage neurons by activating the p75 neurotrophin receptor (p75NTR). However, the signaling pathway leading to neuronal cell death is not completely understood. By using a neuroblastoma cell line devoid of neurotrophin receptors and engineered to express either a full-length or a death domain (DD)-truncated form of p75NTR, we demonstrated that Abeta peptide activates the mitogen-activated protein kinases (MAPKs) p38 and c-Jun N-terminal kinase (JNK). We also found that Abeta peptide induces the translocation of nuclear factor-kappaB (NF-kappaB). These events depend on the DD of p75NTR. Beta-amyloid (Abeta) peptide was found not to be toxic when the above interactors were inhibited, indicating that they are required for Abeta-induced neuronal cell death. p75 neurotrophin receptor (p75NTR)-expressing cells became resistant to Abeta toxicity when transfected with dominant-negative mutants of MAPK kinases 3, 4, or 6 (MKK3, MKK4, or MKK6), the inhibitor of kappaBalpha, or when treated with chemical inhibitors of p38 and JNK. Furthermore, p75NTR-expressing cells became resistant to Abeta peptide upon transfection with a dominant-negative mutant of p53. These results were obtained in the presence of normal p38 and JNK activation, indicating that p53 acts downstream of p38 and JNK. Finally, we demonstrated that NF-kappaB activation is dependent on p38 and JNK activation. Therefore, our data suggest a signaling pathway in which Abeta peptide binds to p75NTR and activates p38 and JNK in a DD-dependent manner, followed by NF-kappaB translocation and p53 activation.
authors.affiliation: Department of Pathology, Section of General Pathology, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy. claudio.costantini@medicina.univr.it
authors.forename: Claudio
authors.initials: C
authors.lastname: Costantini
authors.forename: Filippo
authors.initials: F
authors.lastname: Rossi
authors.forename: Elena
authors.initials: E
authors.lastname: Formaggio
authors.forename: Roberto
authors.initials: R
authors.lastname: Bernardoni
authors.forename: Daniela
authors.initials: D
authors.lastname: Cecconi
authors.forename: Vittorina
authors.initials: V
authors.lastname: Della-Bianca
mesh_terms: D016229:Amyloid beta-Peptides / Q000378:metabolism*; D016923:Cell Death / Q000502:physiology*; D045744:Cell Line, Tumor; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D009447:Neuroblastoma; D009474:Neurons / Q000166:cytology* / Q000378:metabolism; D020800:Receptor, Nerve Growth Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D016229:Amyloid beta-Peptides; D016328:NF-kappa B; D020800:Receptor, Nerve Growth Factor; D016159:Tumor Suppressor Protein p53; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases