Maternal DDB1 regulates apoptosis and lineage differentiation in porcine preimplantation embryos.

Maternal-effect genes (MEGs) play a critical role in modulating both cellular and molecular biology events in preimplantation embryonic development. Damage-specific DNA binding protein 1 (DDB1) is a gene that participates in meiotic resumption, ovulation, and embryonic stem cell maintenance. Its function in preimplantation development is not well-studied. We aimed to explore the expression pattern, genomic heritage, and potential molecular mechanisms of DDB1 in preimplantation embryos in porcine. In this study, RNA interference, microinjection, RT-qPCR, immunofluorescence staining and single-cell RNA sequencing were used to explore the molecular function of DDB1 in porcine preimplantation embryos. DDB1 was found to be expressed in germinal vesicle (GV) and Meiosis II (MII) oocytes and in preimplantation embryos. We confirmed it is a MEG. DDB1 -deficient blastocysts had a significantly reduced number of trophectoderm cells, an increased apoptotic cell number and increased apoptosis index. According to a next-generation sequencing (NGS) analysis, 236 genes (131 upregulated and 105 downregulated) significantly changed in the DDB1 -deficient morula. The myeloid leukaemia factor 1 (MLF1 ) and yes-associated protein 1 (YAP1 ) expressions were significantly upregulated and downregulated respectively, in the DDB1 -deficient morula. In combination with the decreased expression of TEAD4 , CDX2 , GATA3 , OCT4 , and NANOG and the increased expression of SOX2 in the blastocyst, DDB1 may play a role in determining lineage differentiation and pluripotency maintenance. DDB1 is a MEG and it plays a crucial role in porcine preimplantation embryonic development. This study provides a theoretical basis for further understanding the molecular mechanisms of preimplantation embryo development.