# Dominant‐Negative Effects of p53 R337 Variants in Li–Fraumeni Syndrome: Impact on Tetramer Formation and Transcriptional Activity

## TL;DR

This study shows how p53 mutations in Li–Fraumeni syndrome reduce the function of normal p53 proteins, leading to cancer risk through unstable protein complexes and reduced gene activity.

## Contribution

A novel FRET-based assay was developed to study p53 heterotetramer formation and transcriptional activity in live cells.

## Key findings

- R337C and R337H p53 variants form heterotetramers with wild-type p53 but show significantly reduced transcriptional activity.
- The loss of activity is more pronounced for low-affinity response elements like bax compared to high-affinity elements like CDKN1A.
- These findings reveal a dominant-negative-like effect of p53 mutations in Li–Fraumeni syndrome.

## Abstract

Li–Fraumeni syndrome (LFS) is an inherited cancer predisposition disorder caused by heterozygous TP53 mutations. Among these, missense mutations at Arg337—such as R337C and R337H—are common in LFS patients. Although many studies have characterized individual p53 variants in LFS, the impact of tetramerization domain (TD) mutations on wild‐type (WT) p53 function remains unclear. Herein, a novel FRET‐based assay system that enables the simultaneous detection of heterotetramer formation and p53‐dependent transcriptional activity in live cells is developed. These results show that the heteromultimerization of the R337C variant with WT p53 is only slightly reduced compared to WT homotetramers, yet its transcriptional activity is diminished by over 50%. In contrast, the R337H variant forms heterotetramers at near‐normal levels but exhibits markedly compromised transcriptional activity. These findings reveal a previously unrecognized dominant‐negative‐like effect, suggesting reduced p53 function is due not only to decreased tetramer formation but also to diminished heterotetramer stability. Moreover, the LFS‐associated p53TD variants show a greater loss of activity against the low‐affinity, apoptosis‐inducing bax response element than against the high‐affinity, cell cycle arrest‐related CDKN1A response element. Collectively, this study demonstrates that p53TD mutations can exert dominant‐negative effects, advancing the understanding of p53 heteromultimer function in LFS pathogenesis. These mechanistic insights into p53 heterotetramer stability may not only inform genetic screening strategies for LFS but also support future therapeutic approaches aimed at restoring p53 function by stabilizing mutant tetramers.

Hetero‐tetramer dysfunction: Li–Fraumeni syndrome (LFS) is a hereditary cancer predisposition caused by mutations in the TP53 gene encoding the tumor suppressor p53. It is shown that p53 variants R337C and R337H, found in LFS, impair wild‐type (WT) p53 function by forming heterotetramers with reduced transcriptional activity. This dominant‐negative‐like effect may explain tissue‐specific tumor susceptibility in LFS.© 2025 WILEY‐VCH GmbH