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Tau mRNA isoforms following sciatic nerve axotomy with and without regeneration
1Department of Pharmacology, Loyola University Medical Center, Maywood, IL 60153, USA.
Brain Research. Molecular Brain Research
|August 1, 1997
Summary
Following nerve injury, tau gene expression shifts. Nerve transection, but not crush, reactivates developmental 3R tau mRNA patterns, potentially linking to Alzheimer's disease pathology.
Area of Science:
- Neuroscience
- Molecular Biology
- Cell Biology
Background:
- Microtubule-associated protein tau stabilizes microtubules in neurons.
- Tau protein is a key component of pathological paired helical filaments in Alzheimer's disease (AD).
- Alternative splicing produces 3R tau (developing neurons) and 4R tau (adult neurons) isoforms, with 4R tau having enhanced microtubule binding.
Purpose of the Study:
- To investigate if tau gene expression reverts to a developmental pattern after nerve injury.
- To compare the effects of nerve crush versus nerve transection on tau mRNA isoform expression.
Main Methods:
- Adult rat sciatic nerves were subjected to unilateral crush or transection.
- Tau mRNA isoform expression in the spinal cord was analyzed using reverse transcriptase-polymerase chain reaction (RT-PCR).
Main Results:
- Nerve crush led to decreased 3R and 4R tau mRNA on the injured side, with no change in the 4R/3R ratio.
- Nerve transection resulted in increased 3R tau mRNA and a decreased 4R/3R ratio at later time points (7, 14, 42 days).
Conclusions:
- Nerve transection, unlike crush, recapitulates the developmental pattern of 3R tau gene expression.
- Increased 3R tau mRNA expression following nerve transection may mirror potential mechanisms in Alzheimer's disease, where 3R tau protein promotes paired helical filament formation.