Alterations of the Mdm2 C-Terminus Differentially Impact Its Function In Vivo

Authors

Vinod Pant
Neeraj K Aryal
Shunbin Xiong
Gilda P Chau
Natalie W Fowlkes
Guillermina Lozano

Publication Date

4-1-2022

Journal

Cancer Research

Abstract

Murine double minute 2 (Mdm2) is the principal E3-ubiquitin ligase for p53 and contains a C2H2C4 type RING domain wherein the last cysteine residue is followed by an evolutionarily conserved 13 amino acid C-terminal tail. Previous studies have indicated that integrity of the C-terminal tail is critical for Mdm2 function. Recently, a mutation extending the MDM2 length by five amino acids was identified and associated with enhanced p53 response in fibroblasts and premature aging in a human patient. To investigate the importance of the conserved Mdm2 C-terminal length on p53 regulatory function in vivo, we engineered three novel mouse alleles using CRISPR-Cas9 technology. Genetic studies with these murine models showed that curtailing Mdm2 C-terminal length by even a single amino acid leads to p53-dependent embryonic lethality. Extension of the Mdm2 C-terminal length by five amino acids (QLTCL) yielded viable mice that are smaller in size, exhibit fertility problems, and have a shortened life span. Analysis of early passage mouse embryonic fibroblasts indicated impaired Mdm2 function correlates with enhanced p53 activity under stress conditions. Furthermore, analysis in mice showed tissue-specific alterations in p53 target gene expression and enhanced radiosensitivity. These results confirm the physiological importance of the evolutionarily conserved Mdm2 C-terminus in regulating p53 functions.

Significance: This in vivo study highlights that alterations to the C-terminus of Mdm2 perturb its regulation of the tumor suppressor p53.

Keywords

Animals, Fibroblasts, Mice, Mutation, Protein Binding, Proto-Oncogene Proteins c-mdm2, Tumor Suppressor Protein p53, Ubiquitin-Protein Ligases

DOI

10.1158/0008-5472.CAN-21-2381

PMID

35078816

PMCID

PMC8983537

PubMedCentral® Posted Date

10-1-2022

PubMedCentral® Full Text Version

Author MSS

Published Open-Access

yes