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Antibody to beta-amyloid precursor protein recognizes an intermediate filament-associated protein in Alzheimer's and
N P Dooley1, S Gauthier, H D Durham
1Department of Neurology and Neurosurgery, McGill University, Montreal, Canada.
Abstract:
The expression of beta-amyloid precursor protein (BAPP) and its mRNAs was studied in fibroblasts obtained from patients afflicted with Alzheimer's disease (AD) and age-matched controls. Using reverse transcriptase-polymerase chain reaction (RT-PCR), transcripts corresponding to 770, 751, 714, and 695 amino acids were detected in both AD and control fibroblasts. Antibody 22C11 against BAPP (Boehringer Mannheim) labeled an intracellular protein, specifically localized to the intermediate filament network. In addition to bands of the predicted molecular weights for BAPP (120-135 kDa), Western blotting revealed a 57 kDa band which was not evident in samples of human brain. As cytoskeletal elements are vital in maintaining cellular architecture and various cell interactions, localization of BAPP or a related molecule to the cytoskeleton suggests a possible structural role for this protein within the cell.
Insights
Beta-amyloid precursor protein (BAPP) and its mRNAs are expressed in Alzheimer's disease (AD) fibroblasts. This protein may have a structural role in the cytoskeleton, as indicated by its localization to intermediate filaments.
Area of Science:
- Neuroscience
- Cell Biology
Background:
- Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the accumulation of beta-amyloid plaques.
- The role of beta-amyloid precursor protein (BAPP) in AD pathogenesis is complex and not fully understood.
- Investigating BAPP expression and localization in peripheral cells like fibroblasts may offer insights into cellular mechanisms relevant to AD.
Purpose of the Study:
- To investigate the expression of beta-amyloid precursor protein (BAPP) and its messenger RNAs (mRNAs) in fibroblasts from Alzheimer's disease (AD) patients.
- To determine the cellular localization of BAPP within these fibroblasts.
- To identify potential novel BAPP-related proteins or fragments.
Main Methods:
- Fibroblast cultures were established from AD patients and age-matched controls.
- Reverse transcriptase-polymerase chain reaction (RT-PCR) was employed to detect BAPP mRNA transcripts.
- Western blotting and immunocytochemistry using the 22C11 antibody were used to analyze BAPP protein expression and localization.
Main Results:
- BAPP and its various mRNA transcripts (770, 751, 714, 695 amino acids) were detected in both AD and control fibroblasts.
- Immunocytochemistry revealed that BAPP localizes to the intermediate filament network within the cell.
- Western blotting identified BAPP (120-135 kDa) and an additional 57 kDa band not observed in human brain samples.
Conclusions:
- Beta-amyloid precursor protein (BAPP) is expressed in fibroblasts and shows specific localization to the cytoskeleton.
- The presence of BAPP within the intermediate filament network suggests a potential structural role for this protein.
- Further research is warranted to elucidate the function of BAPP and its potential fragments in cellular structure and in the context of Alzheimer's disease.