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The mouse cpp32 mRNA transcript is early up-regulated in axotomized motoneurons following facial nerve transection
1University Hospital Geneva, Department of Neuropsychiatry, Switzerland. fabienne.debilbao@medecine.unige.ch
Abstract:
In adult mice, axotomy of facial motoneurons induces apoptotic cell death. Cpp32, Bax and Bcl-xl are regulators of this type of cell death in the central nervous system. Using in situ hybridization, we have studied the kinetics of expression of cpp32, bax and bcl-xl mRNAs after a fatal lesion of the facial nerve in wild-type and Bcl-2 transgenic mice, where cell death is known to be prevented. In both strains of mice, cpp32 mRNA was up-regulated by 12 h following axotomy whereas changes in bax mRNA expression occurred later (from 3 days). These results provide information on the timing of molecular processes involved in cell death and could be helpful in determining a critical period during which they may be blocked.
Insights
Axotomy of facial motoneurons triggers cell death regulated by Cpp32, Bax, and Bcl-xl. Gene expression timing reveals critical windows for blocking apoptosis in the central nervous system.
Area of Science:
- Neuroscience
- Molecular Biology
- Cell Death Research
Background:
- Facial motoneuron axotomy in adult mice induces programmed cell death (apoptosis).
- Key regulators of this central nervous system cell death include Cpp32, Bax, and Bcl-xl.
- Bcl-2 transgenic mice are known to prevent this type of cell death.
Purpose of the Study:
- To investigate the temporal expression patterns of cpp32, bax, and bcl-xl messenger RNAs (mRNAs) following facial nerve axotomy.
- To compare these expression kinetics in wild-type mice with those in Bcl-2 transgenic mice.
- To identify critical time periods for molecular intervention in the cell death pathway.
Main Methods:
- In situ hybridization was employed to analyze mRNA expression levels.
- Facial nerve axotomy was performed on adult wild-type and Bcl-2 transgenic mice.
- Kinetic analysis of gene expression was conducted at various time points post-axotomy.
Main Results:
- Cpp32 mRNA levels increased within 12 hours after axotomy in both mouse strains.
- Changes in Bax mRNA expression were observed later, starting around 3 days post-axotomy.
- Bcl-xl mRNA expression kinetics were also monitored in relation to cell death regulation.
Conclusions:
- The study elucidates the distinct timing of molecular events, specifically the upregulation of Cpp32 and Bax, during axotomy-induced motoneuron death.
- These findings provide crucial insights into the temporal dynamics of apoptosis regulators in the central nervous system.
- Understanding this timing may facilitate the development of targeted therapeutic strategies to prevent neuronal loss.