Cell Death Differ. 2017 Apr;24(4):575-579. doi: 10.1038/cdd.2016.128. Epub 2017 Feb 17.

The p53 family members have distinct roles during mammalian embryonic development.

Van Nostrand JL¹, Bowen ME¹, Vogel H², Barna M^3,⁴, Attardi LD^1,⁴.

Author information

1: Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, USA.
2: Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA.
3: Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
4: Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA.

Abstract

The p53 tumor suppressor is a member of a multi-protein family, including the p63 and p73 transcription factors. These proteins can bind to the same consensus sites in DNA and activate the same target genes, suggesting that there could be functional redundancy between them. Indeed, double mutant mice heterozygous for any two family member-encoding genes display enhanced cancer phenotypes relative to single heterozygous mutants. However, whether the family members play redundant roles during embryonic development has remained largely unexplored. Although p53^-/-; p73^-/- mice are born and manifest phenotypes characteristic of each of the single mutants, the consequences of combined deficiency of p63 and either p53 or p73 have not been elucidated. To examine the functional overlap of p53 family members during development, we bred and analyzed compound mutant embryo phenotypes. We discovered that double knockout embryos and five allele knockout embryos only displayed obvious defects accounted for by loss of single p53 family members. Surprisingly, at mid-gestation (E11), we identified a single viable triple knockout embryo that appeared grossly normal. Together, these results suggest that the p53 family is not absolutely required for early embryogenesis and that p53 family members are largely non-redundant during early development.

PMID:: 28211873
PMCID:: PMC5384018
DOI:: 10.1038/cdd.2016.128

[Indexed for MEDLINE]

Free PMC Article

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Figure 1

Viability of p53 family compound mutant embryos. (a) The observed numbers (and expected Mendelian numbers) of p53^−/−;p63^−/− embryos recovered at the indicated embryonic (E) stages from intercrosses of p53^+/−;p63^+/− mice. Genotypes were determined by PCR analysis of yolk sac DNA. Primer sequences are available upon request. The total number of conceptuses isolated is indicated. Significance as denoted by P is determined by the χ² test. (b) Whole-mount images of E16.5 p53^−/−;p63^−/− embryo (right) compared to control littermate (left), showing lack of limbs (arrow) and craniofacial defects (arrowhead). Scale bars indicate 1 mM. (c) The observed numbers (and expected Mendelian numbers) of p63^−/−;p73^−/− embryos recovered at the indicated embryonic (E) stages from intercrosses of p63^+/−;p73^+/− mice. Genotypes were determined by PCR analysis of yolk sac DNA. The total number of conceptuses isolated is indicated. Significance as denoted by P is determined by the χ² test. (d) Whole-mount images of E18.5 p63^−/−;p73^−/− embryo (right) compared to control p63-null littermate (left), showing lack of limbs (arrow) and craniofacial defects (arrowhead). Scale bars indicate 1 mM. (e) The observed numbers (and expected Mendelian number) of compound mutant embryos recovered from p53;p63;p73-heterozygous intercrosses at the indicated embryonic (E) ages. Genotypes were determined by PCR analysis of yolk sac DNA. The total number of conceptuses isolated is indicated. Significance as denoted by P is determined by χ² test. Green: double knockout; Blue: five allele knockout; Red: triple knockout. (f) Whole-mount images of E13.5 p53^+/−;p63^−/−;p73^−/− embryo (right) compared to control littermates (left & middle), showing lack of limbs (arrow) and craniofacial defects (arrowhead) in the p63-null embryos. Scale bars indicate 1 mM. (g) PCR analysis for p53, p63 and p73 alleles in triple knockout embryo (*) relative to wild-type, heterozygous, null, and negative (H₂0) controls. DNA was derived from embryonic tail. (h) Whole-mount images of ethidium bromide-stained UV-imaged p53^−/−;p63^−/−;p73^−/− embryo (right) at E11.0 compared to control littermates (left). The p53^−/−; p63^−/−; p73^−/− embryo has retarded limb development (arrow). Scale bars indicate 500 microns. Mice were maintained on a mixed 129/Sv;C57BL/6J background. Animal work was done according to the Stanford University APLAC

The p53 family members have distinct roles during mammalian embryonic development

Cell Death Differ. 2017 Apr;24(4):575-579.