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Heat shock-mediated cell cycle arrest is accompanied by induction of p21 CKI
1Department of Neurosurgery, Nagoya City University Medical School, Japan. tfuse@cmews2.med.nagoya-cu.ac.jp
Abstract:
Heat shock induces several events in cells including a series of gene expressions and cell cycle arrest. Recently, several types of cell cycle arrest have been related to the function of cyclin-dependent kinase inhibitors (CKI). Here we show that heat shock treatment up-regulates p21 CKI mRNA and protein in A172 glioma cells and arrests the cell cycle at the G1 phase, p53-deficient cell lines, MDAH041 and T98G, also showed a significant increase in p21 CKI expression after heat stress, indicating that the induction involves a p53-independent pathway. The kinetics of this transient induction, which is not affected by cycloheximide, demonstrate that p21 CKI is an immediate-early response gene.
Insights
Heat shock rapidly increases p21 cyclin-dependent kinase inhibitor (CKI) expression and causes G1 cell cycle arrest. This induction occurs independently of p53 and indicates p21 CKI is an immediate-early response gene.
Area of Science:
- Cellular biology
- Molecular biology
- Cancer research
Background:
- Heat shock triggers cellular responses, including gene expression and cell cycle arrest.
- Cyclin-dependent kinase inhibitors (CKIs) are implicated in regulating cell cycle progression.
- The role of heat shock in CKI regulation, particularly in p53-deficient cells, requires further elucidation.
Purpose of the Study:
- To investigate the effect of heat shock on p21 CKI expression in glioma cells.
- To determine if p21 CKI induction by heat shock is dependent on p53.
- To characterize the kinetics of p21 CKI expression following heat stress.
Main Methods:
- Treatment of A172, MDAH041, and T98G cells with heat shock.
- Analysis of p21 CKI mRNA and protein levels using quantitative methods.
- Cell cycle analysis to determine phase distribution.
- Experiments with cycloheximide to assess protein synthesis dependence.
Main Results:
- Heat shock significantly up-regulated p21 CKI mRNA and protein in A172 glioma cells.
- p21 CKI expression increased in p53-deficient cell lines (MDAH041, T98G) after heat stress.
- Cell cycle arrest at the G1 phase was observed following heat shock.
- The induction of p21 CKI was transient, not affected by cycloheximide, and occurred independently of p53.
Conclusions:
- Heat shock induces p21 CKI expression and G1 cell cycle arrest through a p53-independent pathway.
- p21 CKI is identified as an immediate-early response gene to heat stress.
- These findings contribute to understanding cellular stress responses and CKI regulation in cancer cells.