Pierce1, a novel p53 target gene contributing to the ultraviolet-induced DNA damage response

Area of Science:

• Molecular Biology
• Cancer Biology
• Genetics

Background:

• Retinoblastoma (Rb) and p53 are critical tumor suppressor genes frequently mutated in human cancers.
• Rb and p53 mutually regulate each other's functions.
• Rb deficiency leads to altered gene expression, necessitating further investigation.

Purpose of the Study:

• To identify novel genes regulated by p53.
• To investigate the role of the novel transcript Pierce1 in DNA damage response.
• To elucidate the regulatory mechanisms of Pierce1 expression and function.

Main Methods:

• Gene expression analysis in Rb-deficient mouse embryonic fibroblasts (MEFs).
• Reporter assays to study Pierce1 promoter activity in response to p53 and E2F1.
• Genotoxic stress induction (UVC irradiation) and assessment of Pierce1 expression and stability.
• Western blotting and proteasomal degradation assays.
• siRNA-mediated knockdown of Pierce1 and analysis of DNA damage response pathways.

Main Results:

• Pierce1 was identified as a novel transcript upregulated in Rb-deficient MEFs.
• Pierce1 is a direct transcriptional target of p53, activated via two cis-elements in its promoter.
• Pierce1 expression is induced by genotoxic stresses that activate p53 and is dependent on p53.
• Pierce1 protein is stabilized by UVC irradiation through ATR signaling, inhibiting proteasomal degradation.
• Knockdown of Pierce1 impaired the DNA damage response to UVC irradiation and reduced p53 target gene expression.

Conclusions:

• Pierce1 is a critical p53 target gene involved in the DNA damage response.
• Pierce1 plays a significant role in maintaining genomic integrity under genotoxic stress.
• The findings highlight a novel mechanism involving Pierce1 in cellular response to DNA damage.