Embryonic POU5F1 is Required for Expanded Bovine Blastocyst Formation

Area of Science:

• Reproductive Biology
• Developmental Biology
• Gene Editing

Background:

• POU5F1 is a crucial transcription factor regulating cell pluripotency and early embryonic development.
• Its specific role in blastocyst formation and lineage specification varies across mammalian species.
• The function of embryonic POU5F1 in cattle has not been previously understood.

Purpose of the Study:

• To investigate the function of the POU5F1 gene in early bovine embryo development.
• To determine the effects of POU5F1 gene disruption on blastocyst formation and cell lineage specification in cattle.
• To compare the role of bovine POU5F1 with its counterparts in other mammalian species.

Main Methods:

• CRISPR/Cas9 gene editing system was employed for targeted disruption of the POU5F1 gene.
• Direct injection of CRISPR/Cas9 components into bovine zygotes was performed.
• Embryo development was monitored, and gene expression (SOX2, CDX2) was analyzed in POU5F1 knockout embryos.

Main Results:

• Targeted disruption of the bovine POU5F1 gene resulted in a complete failure of blastocyst formation.
• Embryonic development arrested at the morula stage in POU5F1 knockout embryos.
• While SOX2 expression initiation was unaffected, CDX2 expression was aberrant in the absence of POU5F1.
• POU5F1 knockout morulas showed similar developmental rates and cell numbers as control embryos by day 5.

Conclusions:

• POU5F1 is essential for blastocyst formation and early embryonic development in cattle.
• The observed phenotype in bovine POU5F1 knockout embryos suggests conserved functions with human embryonic POU5F1, differing from mice.
• The cattle model, with its conserved transcriptional regulation and efficient gene editing, offers valuable insights into human embryo biology and has potential applications in agriculture and assisted reproductive technologies.