Related Experiment Videos
p53-mediated negative regulation of stathmin/Op18 expression is associated with G(2)/M cell-cycle arrest
J I Johnsen1, O N Aurelio, Z Kwaja
1Department of Virology, Faculty of Medicine, University of Tromso, Tromso Norway.
Abstract:
Utilizing the technique of differential display of mRNA, we have identified p53-responsive genes that are transcriptionally up- or down-regulated as cells enter growth arrest. One gene that was down-regulated, pong16, was found to be identical to stathmin/Op18, a protein involved in the regulation of microtubule dynamics. Evidence that p53 is directly or indirectly involved in negative regulation of stathmin/Op18 expression includes the following: (i) p53-mediated growth inhibition is associated with repression of stathmin/Op18 expression following serum stimulation, (ii) reporter gene assays revealed p53-mediated repression of stathmin/Op18 promoter activity and (iii) constitutive over-expression of stathmin/Op18 bypasses a p53-mediated G(2)/M arrest in the cell cycle. These results suggest that p53-mediated negative regulation of stathmin/Op18 plays an important role in cell-cycle control.
Insights
The tumor suppressor p53 negatively regulates the expression of stathmin/Op18, a protein crucial for microtubule dynamics. This regulation is vital for controlling cell growth arrest and cell-cycle progression.
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- The p53 tumor suppressor is a key regulator of cellular responses to stress, including growth arrest.
- Stathmin/Op18 is a protein that modulates microtubule dynamics, influencing cell division.
- Understanding the interplay between p53 and genes involved in cell-cycle control is critical for cancer research.
Purpose of the Study:
- To identify genes regulated by p53 during growth arrest.
- To investigate the role of stathmin/Op18 in p53-mediated cell-cycle control.
Main Methods:
- Differential display of mRNA to identify p53-responsive genes.
- Reporter gene assays to assess promoter activity.
- Cell-cycle analysis to evaluate the impact of stathmin/Op18 expression.
Main Results:
- Identified stathmin/Op18 (pong16) as a p53-repressed gene during growth arrest.
- Demonstrated p53-mediated repression of stathmin/Op18 promoter activity.
- Showed that stathmin/Op18 overexpression can bypass p53-induced G2/M cell-cycle arrest.
Conclusions:
- p53 negatively regulates stathmin/Op18 expression.
- p53-mediated repression of stathmin/Op18 is important for cell-cycle arrest.
- This pathway is a significant component of p53's tumor suppressor function.