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Brain Res. 2008 Mar 10;1198:204-12. doi: 10.1016/j.brainres.2008.01.031. Epub 2008 Jan 26.

Phosphorylation of beta-amyloid precursor protein (APP) cytoplasmic tail facilitates amyloidogenic processing during apoptosis.

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  • 1Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA.

Abstract

Secretion and progressive cerebral accumulation of beta-amyloid peptides (Abeta) derived by endoproteolytic ("amyloidogenic") processing of beta-amyloid precursor protein (APP) represent collectively an early and necessary event in the pathogenesis of Alzheimer's disease. We previously demonstrated that secretion of the neurotoxic species Abeta42 increases during staurosporine-induced apoptosis in undifferentiated PC12 cells, in an endocytosis-dependent manner. In the present study, we tested whether phosphorylation of the APP cytoplasmic-tail is contributory to this apoptosis-related increased Abeta-secretory response. We demonstrate that cytoplasmic-tail phosphorylation specifically at amino-acid residue T668 (APP-695 numbering) increases during staurosporine-induced apoptosis, in parallel with activation of the mitogen-activated, proline-directed serine/threonine protein kinase ERK1. We demonstrate additionally that specific ERK inhibition during staurosporine induction, with serum-free conditions, results in down-regulation of APP phosphorylation at T668, together with attenuation of the increased Abeta-secretory response. These results are consistent with APP cytoplasmic-tail phosphorylation at T668 during apoptosis as contributory to increased Abeta42 secretion originating from the endocytotic pathway, likely with cell-line restriction.

[PubMed - indexed for MEDLINE]
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