The transcription factors FOXO4 and p53 regulate aging, and their deregulation has been linked to several diseases, including cancer. Under stress conditions, cellular senescence is promoted by p53 sequestration and senescence-associated protein p21 transcriptional upregulation induced by interactions between the FOXO4 Forkhead DNA-binding domain and the p53 transactivation domain. However, the molecular details of these interactions remain unclear. Here, we report that these interactions between p53 and FOXO4 domains are highly heterogeneous. The p53 transactivation domain primarily interacts with the region formed by the N-terminal helical bundle of the FOXO4 Forkhead domain but retains a substantial degree of flexibility in the complex. In addition, NMR data-driven molecular simulations suggest that p53 interacts with FOXO4 through multiple binding modes. Overall, our findings not only provide the structural insights into interactions between FOXO4 and p53 but also highlight their potential as targets for developing senolytic compounds.

• MeSH
• Forkhead Transcription Factors * metabolism   chemistry   genetics   MeSH
• Humans MeSH
• Tumor Suppressor Protein p53 * metabolism   chemistry   genetics   MeSH
• Protein Domains MeSH
• Cell Cycle Proteins * metabolism   chemistry   MeSH
• Molecular Dynamics Simulation MeSH
• Transcription Factors * metabolism   chemistry   genetics   MeSH
• Protein Binding MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Forkhead Transcription Factors * MeSH
• FOXO4 protein, human MeSH Browser
• Tumor Suppressor Protein p53 * MeSH
• Cell Cycle Proteins * MeSH
• TP53 protein, human MeSH Browser
• Transcription Factors * MeSH

Transcription factor p53 protects cells against tumorigenesis when subjected to various cellular stresses. Under these conditions, p53 interacts with transcription factor Forkhead box O (FOXO) 4, thereby inducing cellular senescence by upregulating the transcription of senescence-associated protein p21. However, the structural details of this interaction remain unclear. Here, we characterize the interaction between p53 and FOXO4 by NMR, chemical cross-linking, and analytical ultracentrifugation. Our results reveal that the interaction between p53 TAD and the FOXO4 Forkhead domain is essential for the overall stability of the p53:FOXO4 complex. Furthermore, contacts involving the N-terminal segment of FOXO4, the C-terminal negative regulatory domain of p53 and the DNA-binding domains of both proteins stabilize the complex, whose formation blocks p53 binding to DNA but without affecting the DNA-binding properties of FOXO4. Therefore, our structural findings may help to understand the intertwined functions of p53 and FOXO4 in cellular homeostasis, longevity, and stress response.

• Keywords
• DNA binding, Forkhead box O 4, nuclear magnetic resonance, protein-protein interaction, senescence, transcription factor p53,
• MeSH
• DNA chemistry   MeSH
• Forkhead Transcription Factors * chemistry   genetics   metabolism   MeSH
• Tumor Suppressor Protein p53 * genetics   metabolism   MeSH
• Cell Cycle Proteins metabolism   MeSH
• Protein Binding MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• DNA MeSH
• Forkhead Transcription Factors * MeSH
• Tumor Suppressor Protein p53 * MeSH
• Cell Cycle Proteins MeSH