Posttranslational regulation of p53 tumor suppressor protein function

Area of Science:

• Molecular Biology
• Cancer Research
• Genetics

Background:

• The p53 gene is the most common target of alteration (deletion and mutation) in human cancers.
• Wild-type p53 protein restricts cell growth in G1 phase by regulating gene transcription and DNA replication.
• Understanding p53's growth restriction mechanism requires identifying its target genes and interacting proteins.

Purpose of the Study:

• To investigate the mechanism of p53's role in regulating cell growth.
• To propose an expanded model for p53 biochemical function regulation.
• To explore how p53 conformation influences its biological activity.

Main Methods:

• Building upon the conformational hypothesis of p53 function.
• Incorporating binding proteins, kinases/phosphatases, redox modifiers, and oligomerization into a regulatory model.
• Analyzing how different p53 conformations interact with gene promoters and DNA replication origins.

Main Results:

• Mutations in human cancers often lock p53 into a growth-promoting conformation.
• The proposed model suggests p53 conformation dictates interactions with regulatory complexes, mediating distinct cellular effects.
• p53's conformational state influences its ability to repress or activate other transcription factors, affecting gene regulation indirectly.

Conclusions:

• Cell- and tissue-specific expression of p53-binding proteins and enzymes regulates p53 interactions with gene promoters.
• Defects in p53 regulatory proteins may contribute to tumorigenesis even in the presence of normal p53.
• Dysregulation of the p53 biochemical pathway could be more widespread in human cancers than currently understood.