DUXA is not essential for parthenogenetic blastocyst formation but regulates cell proliferation in porcine embryos

In brief: The transcription factor Dux regulates embryonic genome activation in mice, yet the function of its porcine ortholog, DUXA, remains unclear. Findings from this study suggest that although DUXA seems not essential for parthenogenetic blastocyst formation in pigs, it may play a role in modulating embryonic cell proliferation and the DNA damage response. Abstract: Embryonic genome activation (EGA) marks the onset of transcriptional autonomy in the developing embryo, a process that is still not well characterized in pigs. Emerging evidence suggests that chromatin remodeling events during EGA and DNA damage response (DDR) may share regulatory mechanisms. In mouse and human embryos, the double homeobox (Dux) transcription factor acts as a pioneer regulator of EGA and may also contribute to DDR. However, the role of the porcine ortholog, DUXA, in early embryogenesis is not well understood. In this study, we show that DUXA mRNA is highly expressed in porcine embryos at the EGA stage, with levels declining at post-EGA and blastocyst stages. Attenuation of DUXA mRNA did not impair blastocyst formation or lineage allocation to the inner cell mass and trophectoderm. Unexpectedly, DUXA mRNA attenuation increased total cell number in both blastocysts and embryos arrested prior to blastocoel formation. DUXA mRNA attenuation decreased mRNA levels of EGA-related (EIF1AX), cell cycle checkpoint (CHEK1), and DDR-associated genes (BRCA1), and was accompanied by increased DNA damage at late/post-EGA stages. Induced DNA damage upregulated transcripts of EGA-related (DPPA2, KDM5B, EIF2A) and DDR-associated genes (P53, RAD51) on day 4 of development. Interestingly, DNA damage induction in DUXA mRNA-attenuated embryos abrogated the impact on cell proliferation and enhanced transcript levels of checkpoint (CHEK1 and XIAP) and DDR (P53, KU-70 and KU-80) genes. These findings suggest that while DUXA is not essential for parthenogenetic blastocyst formation in pigs, it may play a regulatory role in embryonic cell proliferation, checkpoint activation, and the DNA damage response.