Examination of the interactions of the amyloid precursor protein carboxyl terminus to intracellular protein: possible role in apoptosis.
1. The carboxyl terminus of the amyloid precursor protein (APP) has several identified regions that may potentially contribute to the pathogenic effects of Alzheimer's disease (AD). To examine these effects, the authors iodinated a short synthetic peptide corresponding to amino acids 679-687 of APP695. They also produced a [35S]-Methionine labeled peptide corresponding to the entire carboxyl 100 amino acids of APP695 via a reticulocyte lysate coupled in vitro transcription/translation system. 2. Human neuroblastoma cells (SK-N-SH) and non-neuronal epithelial cells (RK-13) were cultured, harvested, and lysed. The S1 cell extract fractions were combined with either of the labeled peptides and incubated at different temperatures to allow for interaction and binding of cellular proteins with the peptides. These interactions were identified as gel mobility shift patterns on native PAGE gels. The presence of distinct bands on the gels indicate that the APP C-terminus interacts with several intracellular proteins, some of which may be detrimental to the cell. The authors have tested the possibility that the accumulation of C-terminal proteins may result in apoptosis. 3. Apoptosis in neural cells is one detrimental effect that has been attributed to APP. The authors examined hippocampal tissue sections from Alzheimer's disease (AD) and age-matched normal control patients for a difference in the number of apoptotic nuclei present using an in situ apoptosis detection kit that labels the numerous free DNA ends present in apoptotic nuclei. The number of apoptotic nuclei found in AD neuronal tissue was significantly higher than in normal tissue.
Daly
J
J
Department of Microbiology and Immunology, University of Louisville School of Medicine, KY, USA.
Lahiri
D K
DK
Kotwal
G J
GJ
D000544:Alzheimer Disease / Q000378:metabolism; D016564:Amyloid beta-Protein Precursor / Q000633:toxicity*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001932:Brain Neoplasms / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006624:Hippocampus / Q000187:drug effects / Q000473:pathology; D006801:Humans; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D008715:Methionine / Q000378:metabolism; D051379:Mice; D009410:Nerve Degeneration / Q000473:pathology; D009447:Neuroblastoma / Q000378:metabolism; D010446:Peptide Fragments / Q000633:toxicity*; D013462:Sulfur Radioisotopes; D014407:Tumor Cells, Cultured
D016564:Amyloid beta-Protein Precursor; D007457:Iodine Radioisotopes; D010446:Peptide Fragments; D013462:Sulfur Radioisotopes; D008715:Methionine