WNT signaling during oocyte-to-embryo stages
The WNT signaling pathway is a central regulator of cell polarity, adhesion, cytoskeletal dynamics, and lineage specification during early embryonic development. Although its roles have been extensively studied in murine and human models, the temporal regulation and pathway architecture of WNT signaling during early porcine development remain poorly defined. Here, we performed a comprehensive transcriptomic analysis to character-ize WNT pathway dynamics across key stages of pig in vitro development, including im-mature oocytes (IMO), mature oocytes (MO), zygotes (ZY), cleaved embryos (2–4 cells; CL), and blastocysts (BL). Global analyses revealed major transcriptomic transitions dur-ing oocyte maturation and blastocyst formation, whereas zygotes and cleaved embryos exhibited highly similar expression profiles. Module-based and gene-level analyses showed that oocyte maturation is associated with increased expression of extracellular WNT antagonists and components of the ß-catenin destruction complex, together with selective regulation of Frizzled receptors, consistent with tight control of canonical WNT signaling at the MII stage. Following fertilization, this inhibitory configuration was par-tially relieved, alongside transient upregulation of specific WNT ligands, transcriptional mediators, and adhesion-related components during zygotic genome activation and early cleavage. At the blastocyst stage, WNT signaling became increasingly associated with planar cell polarity and epithelial organization modules. Together, the data reveal a highly dynamic and stage-specific restructuring of WNT signaling during early porcine devel-opment. Our findings indicate that precise temporal modulation-rather than uniform acti-vation-of WNT pathway components accompanies the porcine oocyte-to-embryo transi-tion, providing a molecular framework to better understand early developmental regulation and offering insights relevant to reproductive biotechnology and developmental biology.