Journals of Gerontology Series A: Biological Sciences and Medical Sciences, Vol 53, Issue 3 B186-B190, Copyright © 1998 by The Gerontological Society of America
The production of the Alzheimer amyloid precursor protein (APP) in extraneuronal tissue does not increase in old age
E Niederwolfsgruber, TL Schmitt, I Blasko, K Trieb, MM Steger, C Maczek, J Hager, K Bobak, E Steiner and B Grubeck-Loebenstein
Institute for Biomedical Aging Research, Austrian Academy of Sciences, Innsbruck, Austria.
Alzheimer's disease (AD) is characterized by the cerebral deposition of
beta-amyloid (A beta). A beta plaques also occur in the brains of healthy
aged individuals, and A beta concentrations are increased in the
cerebrospinal fluid (CSF) in old age. Based on results from an in vitro
senescence model on human fibroblasts, it was proposed that the production
of the beta-amyloid precursor protein (APP) was increased during aging. No
information was available as to whether APP production was also augmented
in aged humans. It was therefore the aim of the present study to analyze
APP in connective tissue, skeletal muscle, peripheral blood mononuclear
cells, and serum samples from young and aged healthy individuals. APP
production was assessed by Northern and Western blotting. The expression of
the different APP isoforms was studied by reverse transcription-polymerase
chain reaction (RT-PCR) technique. The results demonstrate that APP
messenger ribonucleic acid (mRNA) and protein concentrations were identical
in blood and tissue samples from young and aged individuals and that there
were no age- dependent changes in the APP isoform production pattern. Thus,
our data strongly argue against the possibility of an altered production of
APP during healthy aging and underline the point that in vitro aging models
may not accurately reflect the in vivo situation.
