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Expression and cellular localization of amyloid beta-protein precursor transcripts in normal human brain and in
M G Spillantini1, S P Hunt, J Ulrich
1Medical Research Council Laboratory of Molecular Biology, Cambridge, U.K.
Abstract:
Two classes of amyloid beta-protein precursors which differ by the presence of a serine protease inhibitor domain have been described. We have used synthetic oligonucleotide probes to investigate the tissue distribution and cellular localization of mRNAs encoding the two classes of amyloid beta-protein precursors. RNA blot analysis showed that transcripts encoding the protease inhibitor sequence are ubiquitously expressed in peripheral and central tissues. By contrast, transcripts lacking the protease inhibitor domain were only found in the central nervous system. By in situ hybridization on cerebral cortex and hippocampal formation both types of transcripts were present exclusively in nerve cells and they appeared to be produced by the same cells. A reduction in the transcript lacking the protease inhibitor domain was observed in frontal cortex from Alzheimer's disease patients. The present results indicate that there exists no correlation between the distribution of amyloid amyloid beta-protein precursor mRNAs and the tissue and cellular pathology of Alzheimer's disease; they also suggest that an overproduction of amyloid beta-protein precursor mRNA is unlikely to be responsible for amyloid beta-protein deposition in Alzheimer's disease.
Insights
Amyloid precursor protein (APP) mRNA lacking a protease inhibitor domain is specific to the central nervous system. Its reduction in Alzheimer's disease frontal cortex suggests it's not linked to amyloid plaque formation.
Area of Science:
- Neuroscience
- Molecular Biology
- Genetics
Background:
- Two forms of amyloid beta-protein precursor (APP) exist, differing by a serine protease inhibitor (SPI) domain.
- Understanding the distribution and cellular localization of APP mRNA is crucial for elucidating its role in neurological conditions.
Purpose of the Study:
- To investigate the tissue distribution and cellular localization of mRNAs encoding the two classes of APP.
- To examine the potential correlation between APP mRNA levels and Alzheimer's disease pathology.
Main Methods:
- Synthetic oligonucleotide probes were used for detection.
- RNA blot analysis was employed to assess mRNA expression across tissues.
- In situ hybridization was performed on cerebral cortex and hippocampal formation for cellular localization.
Main Results:
- Transcripts encoding the SPI domain were ubiquitously expressed in both central and peripheral tissues.
- Transcripts lacking the SPI domain were exclusively found in the central nervous system, specifically within nerve cells.
- A reduction in the SPI domain-lacking transcript was observed in the frontal cortex of Alzheimer's disease patients.
Conclusions:
- APP mRNA distribution does not correlate with the tissue or cellular pathology observed in Alzheimer's disease.
- Overproduction of APP mRNA is unlikely to be the cause of amyloid beta-protein deposition in Alzheimer's disease.