p53 Mutant p53^N236S Induces Neural Tube Defects in Female Embryos

Area of Science:

• Molecular Biology
• Developmental Biology
• Genetics

Background:

• The tumor suppressor p53 plays a critical role in DNA damage surveillance and stress response, regulating cell cycle arrest and apoptosis.
• Mutations in p53 can lead to oncogenesis through loss-of-function and gain-of-function mechanisms, promoting abnormal cell proliferation.
• Neural tube defects (NTDs) are severe congenital abnormalities affecting the brain and spinal cord, with complex underlying causes.

Purpose of the Study:

• To investigate the in vivo consequences of a specific p53 mutation (Asn-to-Ser at amino acid 236) in a knock-in mouse model.
• To characterize the phenotypic outcomes, including tumorigenesis and developmental abnormalities, associated with the p53N236S mutation.
• To explore the molecular mechanisms underlying the observed p53 mutation-associated phenotypes and identify potential therapeutic rescue strategies.

Main Methods:

• Establishment of a knock-in mouse model (p53N236S) using homologous recombination to introduce the specific p53 amino acid substitution.
• Phenotypic analysis of p53N236S mice, focusing on tumorigenesis and detailed examination of embryonic development, particularly neural tube closure.
• Molecular studies involving gene expression analysis (mRNA and protein levels), epigenetic modifications (H3K27me3), and cell behavior assessments (proliferation, differentiation, apoptosis).
• Genetic rescue experiments by crossing p53N236S mice with Wrn (Werner syndrome) mutant mice to inhibit cell proliferation.

Main Results:

• The p53N236S mutation resulted in a female-specific phenotype of exencephaly and spina bifida, with high occurrence rates in female embryos.
• The mutation led to increased neuronal proliferation, decreased neuronal differentiation, and altered apoptosis, contributing to neurodevelopmental defects.
• Molecularly, p53S decreased UTX expression by increasing Xist transcript, leading to elevated H3K27me3 and repressed Mash1 transcription.
• Inhibition of cell proliferation by crossing with Wrn mice partially rescued the exencephaly phenotype in p53N236S mice.

Conclusions:

• The p53N236S mutation induces female-specific neural tube defects through dysregulation of neurodevelopmental processes.
• The observed phenotype is linked to altered epigenetic regulation (H3K27me3) and gene expression (UTX, Mash1) impacting neuronal proliferation, differentiation, and apoptosis.
• Targeting cell proliferation pathways, such as through Wrn deficiency, offers a potential strategy for rescuing p53-associated NTDs.