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Bcl-2 protects against apoptosis-related microtubule alterations in neuronal cells
R Nuydens1, G Dispersyn, G Van Den Keiboom
1Department of Cell Physiology, Janssen Research Foundation, Beerse, Belgium.
Abstract:
Bcl-2 is a gene with clear anti-apoptotic properties in neurodegenerative conditions. One of the earliest hallmarks of degeneration in neuronal cell cultures is the loss of neurite morphology. Therefore the effect of Bcl-2 on neuronal morphology and microtubule stability was studied in nerve growth factor differentiated PC12 cells. Microtubule dynamics were modulated using the microtubule stabilizer taxol and the microtubule destabilizer, okadaic acid, a protein phosphatase inhibitor. It was shown that Bcl-2 protects against both taxol- and okadaic acid induced neurite retraction. Bcl-2 overexpression also significantly reduced the increased ratio of acetylated tubulin over total tubulin induced by taxol treatment. Interestingly, Bcl-2 attenuates the decrease of the same ratio after exposure to okadaic acid, suggesting that Bcl-2 is able to normalize the level of acetylated tubulin. In addition, cell death and nuclear fragmentation, induced by okadaic acid, were reduced in Bcl-2 overexpressing cells. This protection is either downstream or independent of tau phosphorylation as quantitative immunocytochemistry with AT8 showed that Bcl-2 did not modify the level of tau phosphorylation. The data suggest that the protective effect of Bcl-2 on the neuronal cytoskeleton is probably linked to changes in the post-translational modification of tubulin.
Insights
The Bcl-2 gene protects neurons by stabilizing their structure and preventing cell death. It influences microtubule stability and tubulin modification, crucial for neuronal health in neurodegenerative conditions.
Area of Science:
- Neuroscience
- Cell Biology
- Molecular Biology
Background:
- Neurodegenerative diseases are characterized by neuronal cell death and loss of neurite morphology.
- The anti-apoptotic gene Bcl-2 plays a crucial role in neuronal survival.
- Microtubule stability is essential for maintaining neuronal structure and function.
Purpose of the Study:
- To investigate the effect of Bcl-2 on neuronal morphology and microtubule stability in PC12 cells.
- To determine if Bcl-2 influences tubulin post-translational modifications.
- To explore the protective mechanisms of Bcl-2 against neurotoxic insults.
Main Methods:
- Overexpression of Bcl-2 in nerve growth factor-differentiated PC12 cells.
- Modulation of microtubule dynamics using taxol (stabilizer) and okadaic acid (destabilizer).
- Assessment of neurite morphology, microtubule stability, tubulin acetylation, and tau phosphorylation.
Main Results:
- Bcl-2 overexpression protected against taxol- and okadaic acid-induced neurite retraction.
- Bcl-2 normalized the ratio of acetylated tubulin to total tubulin under both stabilizing and destabilizing conditions.
- Bcl-2 reduced okadaic acid-induced cell death and nuclear fragmentation, independent of tau phosphorylation.
Conclusions:
- Bcl-2 exerts a protective effect on the neuronal cytoskeleton, likely through modulation of tubulin post-translational modifications.
- Bcl-2's anti-apoptotic function in neurodegeneration may be linked to its influence on microtubule dynamics and stability.
- These findings highlight Bcl-2 as a potential therapeutic target for neurodegenerative disorders.