Stage-specific remodeling of WNT signaling during oocyte-to-embryo transition in pigs
The WNT signaling pathway is a central regulator of cell polarity, adhesion, cytoskele-tal dynamics, and lineage specification during early embryonic development. Although its roles have been extensively studied in murine and human models, the temporal reg-ulation and pathway architecture of WNT signaling during early porcine development remain poorly defined. Here, we performed a comprehensive transcriptomic analysis to characterize WNT pathway dynamics across key stages of pig in vitro development, including immature oocytes (IMO), mature oocytes (MO), zygotes (ZY), cleaved em-bryos (2–4 cells; CL), and blastocysts (BL). Global analyses revealed major tran-scriptomic transitions (FDR < 0.05; |Fold Change| = 2) during oocyte maturation and blastocyst formation, whereas zygotes and cleaved embryos exhibited highly similar expression profiles. Module-based and gene-level analyses showed that oocyte matura-tion 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 partially relieved, alongside transient upregulation of specific WNT ligands, transcriptional mediators, and adhesion-related components during zygotic genome activation and early cleav-age. At the blastocyst stage, WNT signaling became increasingly associated with pla-nar cell polarity and epithelial organization modules. Together, the data reveal a high-ly dynamic and stage-specific restructuring of WNT signaling during early porcine development. Our findings indicate that precise temporal modulation-rather than uni-form activation-of WNT pathway components accompanies the porcine oocyte-to-embryo transition, providing a molecular framework to better understand early devel-opmental regulation and offering insights relevant to reproductive biotechnology and developmental biology.