Villa A, Santiago J, García-Silva S, Ruiz-León Y, Pascual A. Serum is required for release of Alzheimer's amyloid precursor protein in neuroblastoma cells.
Neurochem Int 2002;
41:261-9. [PMID:
12106777 DOI:
10.1016/s0197-0186(02)00019-0]
[Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The beta-amyloid peptide, the major component of the senile plaques that characterize Alzheimer's disease, is generated from a set of alternatively spliced beta-amyloid precursor proteins (APPs), which are proteolytically cleaved by the action of a set of enzymes referred to generically as secretases. The major processing pathway involves the proteolytic cleavage of APP by alpha-secretase and results in the release of soluble non-amyloidogenic full-length amino terminal fragments (sAPP), which appear to be involved in neurotrophic events. A reduced production of these neuroprotective sAPP would contribute, together with deposition of the beta-amyloid peptide, to the neurodegenerative processes that lead to the cellular death in Alzheimer's disease. In the present work, we describe a dramatic reduction of sAPP content in medium conditioned by neuronal cells grown under low-serum conditions, when compared with the levels released in the presence of 10% serum. The inhibitory effect on sAPP release appears to be quite specific since that reduction occurs without major changes in cell proliferation, expression of APP-mRNA or intracellular APP levels. Under low-serum conditions, cells showed a more differentiated morphology and no apoptotic signs were observed. Since the alpha-secretase has been described as a membrane anchored protein, our results suggest that the serum contains an essential factor(s) involved in the alpha-secretase activity.
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