The dominant-negative interplay between p53, p63 and p73: A family affair

Area of Science:

• Molecular Biology
• Cancer Biology
• Genetics

Background:

• The tumor suppressor p53's activity is often lost in cancer, even with a wild-type gene present, suggesting dominant-negative effects from mutants and isoforms.
• Related proteins p63 and p73 also show loss of function, hinting at dominant-negative interactions within the p53 family.

Purpose of the Study:

• To investigate the extent and mechanisms of dominant-negative interference among p53, p63, and p73 family members, including hotspot mutants and isoforms.
• To determine if prion-like mechanisms contribute to the loss of function.

Main Methods:

• Utilized a yeast-based system to assess the dominant-negative potential of various p53, p63, and p73 mutants and isoforms.
• Analyzed the molecular mechanisms underlying the observed dominant-negative effects.

Main Results:

• Demonstrated a widespread dominant-negative effect across the p53/p63/p73 family, with all tested p53 loss-of-function mutants and several p53 and p73 isoforms exhibiting this potential.
• Established that the dominant-negative effect on wild-type p53 primarily involves tetramer poisoning via inactive hetero-tetramer formation, refuting a prion-like mechanism.
• Showed that the p53-R175H mutant inhibits p63 and p73 through a mechanism partly dependent on tetramerization.

Conclusions:

• Dominant-negative interactions are prevalent within the p53 family, impacting tumor suppressor functions.
• Tetramer poisoning is the key mechanism for dominant-negative effects of p53 mutants and isoforms, not prion-like behavior.
• Specific mutants like p53-R175H interfere with p63 and p73 through tetramerization-dependent and independent pathways.