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Increased tau messenger RNA in Alzheimer's disease hippocampus
A J Barton1, P J Harrison, A Najlerahim
1Department of Anatomy and Cell Biology, St. Mary's Hospital Medical School, London, United Kingdom.
Abstract:
The microtubule-associated protein tau is present in the pathologic hallmarks of Alzheimer's disease and its production and deposition have been implicated in the pathogenesis of the disease. We detected tau mRNA using in situ hybridization histochemistry in the hippocampus, visual cortex, and cerebellum, and compared its level in Alzheimer's disease with controls. The amount of tau mRNA also was determined as a ratio of total polyadenylated mRNA in each area. A significant and gene-specific increase in tau mRNA hybridization was found in hippocampal fields CA4 and CA3, with a similar trend in the dentate gyrus. In contrast, no change was found in the visual cortex or cerebellum in Alzheimer's disease. Increased hippocampal expression of tau mRNA also was present in cases of non-Alzheimer's dementia. Enhanced tau mRNA may be a marker of attempted plasticity involving the cytoskeleton in neuronal populations affected by various neurodegenerative disorders.
Insights
Increased tau mRNA in the hippocampus, but not the visual cortex or cerebellum, was observed in Alzheimer's disease patients. This suggests tau mRNA may indicate neuronal plasticity in neurodegenerative disorders.
Area of Science:
- Neuroscience
- Molecular Biology
- Pathology
Background:
- Microtubule-associated protein tau is a key component of Alzheimer's disease pathology.
- Tau production and deposition are implicated in Alzheimer's pathogenesis.
Purpose of the Study:
- To investigate tau mRNA levels in specific brain regions of Alzheimer's disease patients compared to controls.
- To determine if increased tau mRNA is specific to Alzheimer's disease or present in other dementias.
Main Methods:
- In situ hybridization histochemistry was used to detect tau mRNA in the hippocampus, visual cortex, and cerebellum.
- Tau mRNA levels were quantified and expressed as a ratio of total polyadenylated mRNA.
Main Results:
- A significant, gene-specific increase in tau mRNA was found in hippocampal fields CA4 and CA3, with a similar trend in the dentate gyrus.
- No significant changes in tau mRNA levels were observed in the visual cortex or cerebellum in Alzheimer's disease.
- Elevated hippocampal tau mRNA expression was also detected in non-Alzheimer's dementia cases.
Conclusions:
- Increased hippocampal tau mRNA expression is a feature of Alzheimer's disease and other neurodegenerative disorders.
- Enhanced tau mRNA may serve as a marker for attempted plasticity in affected neuronal populations.