Increased Foxo3a Nuclear Translocation and Activity is an Early Neuronal Response to ßγ-Secretase-Mediated Processing of the Amyloid-ß Protein Precursor: Utility of an AßPP-GAL4 Reporter Assay.
J Alzheimers Dis
; 61(2): 673-688, 2018.
Article
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| MEDLINE
| ID: mdl-29254083
ABSTRACT
Sequential cleavage of the amyloid-ß protein precursor (AßPP) by BACE1 (ß-secretase) followed by theγ-secretase complex, is strongly implicated in Alzheimer's disease (AD) but the initial cellular responses to these cleavage events are not fully defined. ß-secretase-mediated AßPP processing yields an extracellular domain (sAßPPß) and a C-terminal fragment of AßPP of 99 amino acids (C99). Subsequent cleavage by γ-secretase produces amyloid-ß (Aß) and an AßPP intracellular domain (AICD). A cellular screen based on the generation of AICD from an AßPP-Gal4 fusion protein was adapted by introducing familial AD (FAD) mutations into the AßPP sequence and linking the assay to Gal4-UAS driven luciferase and GFP expression, to identify responses immediately downstream of AßPP processing in neurons with a focus on the transcription factor Foxo3a which has been implicated in neurodegeneration. The K670N/M671L, E682K, E693G, and V717I FAD mutations and the A673T protective mutation, were introduced into the AßPP sequence by site directed mutagenesis. When expressed in mouse cortical neurons, AßPP-Gal4-UAS driven luciferase and GFP expression was substantially reduced by γ-secretase inhibitors, lowered by ß-secretase inhibitors, and enhanced by α-secretase inhibitors suggesting that AICD is a product of the ßγ-secretase pathway. AßPP-Gal4-UAS driven GFP expression was exploited to identify individual neurons undergoing amyloidogenic AßPP processing, revealing increased nuclear localization of Foxo3a and enhanced Foxo3a-mediated transcription downstream of AICD production. Foxo3a translocation was not driven by AICD directly but correlated with reduced Akt phosphorylation. Collectively this suggests that ßγ-secretase-mediated AßPP processing couples to Foxo3a which could be an early neuronal signaling response in AD.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Precursor de Proteína beta-Amiloide
/
Secretasas de la Proteína Precursora del Amiloide
/
Enfermedad de Alzheimer
/
Proteína Forkhead Box O3
/
Neuronas
Tipo de estudio:
Prognostic_studies
Límite:
Animals
Idioma:
En
Revista:
J Alzheimers Dis
Asunto de la revista:
GERIATRIA
/
NEUROLOGIA
Año:
2018
Tipo del documento:
Article
País de afiliación:
Reino Unido