Related Experiment Video
Updated: Apr 29, 2026
Yeast As a Chassis for Developing Functional Assays to Study Human P53
Published on: August 4, 2019
[Roles of p53 in the interaction of p21 and cell cycle proteins induced by benzo [a] pyrene]
Objective:
To investigate the roles of p53 in the interaction of p21, cyclin D1 and CDK4 in human embryonic lung fibroblasts (HELFs) induced by benzo (a) pyrene.
Methods:
p53-H group (cells transfected with p53 small interference RNA plasmid, p53 siRNA) and HELF/CMV group (cells transfected with CMV vector) were treated with 2 micromol/L B [a] P for 24 h, and HELF/CMV + PFT-alpha group (HELF/CMV cells were treated with p53 chemical inhibitor, Pifithrin-alpha) was treated with 2 micromol/L B [a] P and 20 micromol/L PFT-alpha for 24 h. The above three groups set up control groups, respectively. Western blot assay was used to check the levels of p53, phosphorylated p53 at 20 site (p53-ser20), p21, cyclin D1 and CDK4. Immunoprecipitation assay was used to investigate the roles of p53 in the interaction of p21, cyclin D1 and CDK4.
Results:
After inhibition of p53 using PFT-alpha or siRNA, the high levels of p53, p53-ser 20 and p21 induced by B [a] P were markedly decreased. The change of cyclin D1 level was not obsevered and the level CDK4 was free of B [a] P. The combination of p21 and CDK 4 was increased after HELFs exposed to B [a] P, which can not be observed after inhibition p53. The combination of p21 and cyclin D1 was increased with or without the expression of p53 after HELFs exposed to B [a] P. The combination of cyclin D1 and CDK 4 was not affected by B [a] P.
Conclusion:
p53 can affect the combination of p21 and CDK4 in HELFs induced by B [a] P.
Insights
The tumor suppressor p53 influences how p21 interacts with CDK4 in lung fibroblasts exposed to benzo (a) pyrene. Inhibiting p53 reduces p21 and CDK4 complex formation, impacting cell cycle regulation.
Area of Science:
- Cell Biology
- Molecular Biology
- Cancer Research
Background:
- Benzo (a) pyrene is a polycyclic aromatic hydrocarbon found in environmental pollutants.
- p53, p21, cyclin D1, and CDK4 are key regulators of the cell cycle.
- Dysregulation of these proteins is implicated in various cancers.
Purpose of the Study:
- To elucidate the role of p53 in the interaction between p21, cyclin D1, and CDK4.
- To investigate these interactions in human embryonic lung fibroblasts (HELFs) exposed to benzo (a) pyrene (B [a] P).
Main Methods:
- Human embryonic lung fibroblasts (HELFs) were treated with B [a] P.
- p53 was inhibited using small interfering RNA (siRNA) or Pifithrin-alpha (PFT-alpha).
- Western blot and immunoprecipitation assays were used to analyze protein levels and interactions.
Main Results:
- B [a] P increased levels of p53, p53-ser20, and p21, which were reduced upon p53 inhibition.
- p53 inhibition prevented the B [a] P-induced increase in the p21-CDK4 complex.
- Cyclin D1 levels were unaffected, while cyclin D1-CDK4 interaction remained unchanged by B [a] P.
Conclusions:
- p53 plays a critical role in modulating the p21-CDK4 interaction in HELFs exposed to B [a] P.
- These findings highlight a novel mechanism by which p53 influences cell cycle progression under toxicant exposure.
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