The p63 C-terminus is essential for murine oocyte integrity

Anna Maria Lena,Artem Smirnov,Volker Dötsch,Angela Cappello,Francesca Gioia Klinger,Massimo De Felici,Susanne Osterburg,Ivano Amelio,Gerry Melino,Eleonora Candi,Herbert Valensise,Marcel Tuppi,Valerio Rossi,Margherita Annicchiarico-Petruzzelli,Christian Osterburg

doi:10.1038/s41467-020-20669-0

Abstract

The transcription factor p63 mediates distinct cellular responses, primarily regulating epithelial and oocyte biology. In addition to the two amino terminal isoforms, TAp63 and ΔNp63, the 3’-end of p63 mRNA undergoes tissue-specific alternative splicing that leads to several isoforms, including p63α, p63β and p63γ. To investigate in vivo how the different isoforms fulfil distinct functions at the cellular and developmental levels, we developed a mouse model replacing the p63α with p63β by deletion of exon 13 in the Trp63 gene. Here, we report that whereas in two organs physiologically expressing p63α, such as thymus and skin, no abnormalities are detected, total infertility is evident in heterozygous female mice. A sharp reduction in the number of primary oocytes during the first week after birth occurs as a consequence of the enhanced expression of the pro-apoptotic transcriptional targets Puma and Noxa by the tetrameric, constitutively active, TAp63β isoform. Hence, these mice show a condition of ovary dysfunction, resembling human primary ovary insufficiency. Our results show that the p63 C-terminus is essential in TAp63α-expressing primary oocytes to control cell death in vivo, expanding the current understanding of human primary ovarian insufficiency.

Highlights

The transcription factor p63 mediates distinct cellular responses, primarily regulating epithelial and oocyte biology
The results showed a profound phenotype in heterozygous females leading to a condition of ovary disfunction resembling primary ovarian insufficiency (POI) in human females, consistent with descriptions of p63 mutations in human patients affecting fertility (Fig. 6)[37,38,40]
A whole-genome sequencing investigation of POI patients demonstrated that TAp63 truncated variants in the terminal exon are associated with female infertility[40]

Summary

Introduction

The transcription factor p63 mediates distinct cellular responses, primarily regulating epithelial and oocyte biology. A sharp reduction in the number of primary oocytes during the first week after birth occurs as a consequence of the enhanced expression of the pro-apoptotic transcriptional targets Puma and Noxa by the tetrameric, constitutively active, TAp63β isoform. These mice show a condition of ovary dysfunction, resembling human primary ovary insufficiency. The in vivo contributions of p63 N-terminal variants to embryonic development are clearly evident upon selective ΔNp63 and TAp63 knockout (KO) mice[8,10]: striking developmental abnormalities have been observed in ΔNp63-null mice[11], in which the indispensable role of the ΔNp63 isoform in epithelial biology has been genetically demonstrated. TAp63 and yet another, N-terminally elongated isoform, GTAp63α15,16, has been detected in male germ cells, its role in this context has not yet been fully clarified[17,18,19]

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Results

Conclusion