Quantifying the Central Dogma in the p53 Pathway in Live Single Cells

Area of Science:

• Molecular Biology
• Cell Biology
• Genetics

Background:

• Transcription factors (TFs) are crucial regulators of gene expression.
• Quantitative understanding of TF-mediated gene regulation is limited.
• p53 is a key TF involved in DNA damage response, exhibiting dynamic behavior.

Purpose of the Study:

• To quantitatively investigate how p53 dynamics influence p21 transcription and protein levels in individual cells.
• To elucidate the mechanisms by which TF levels regulate target gene output.

Main Methods:

• Developed a system for simultaneous monitoring of p53, p21 mRNA, and p21 protein in single cells.
• Analyzed TF dynamics, transcriptional bursting, and protein accumulation.
• Utilized pharmacological interventions to modulate p53 levels.

Main Results:

• p21 transcription followed p53 dynamics, with mRNA production occurring in bursts.
• p53 levels regulated the probability, but not the magnitude, of p21 transcriptional activation.
• Cell-to-cell variations in p53 led to heterogeneous p21 transcription.
• Elevating p53 increased p21 transcription probability and protein levels.

Conclusions:

• TF dynamics, specifically p53 oscillations, quantitatively regulate target protein production.
• p53 controls the frequency rather than the intensity of target gene transcription.
• This provides insights into TF-mediated gene regulation and cellular responses to damage.