Scientists map genetic switches that turn pig eggs into embryos
Researchers identified how a key signaling pathway reshapes itself as pig eggs mature and begin dividing—discoveries that could improve fertility treatments and livestock breeding. Understanding these molecular transitions in pigs, which share developmental similarities with humans, may unlock better techniques for assisted reproduction across species.
Originaltitel: Stage-specific remodeling of wingless-related integration sites (WNT) signaling during oocyte-to-embryo transition in pigs
WNT-signaleringen regleras helt olika under svin-embryos utveckling från oocyt till blastocyst, vilket kan förbättra reproduktiv bioteknik och gödningsgrader. Forskare från INIA-CSIC och Linköpings universitet kartlade genuttrycket i fem utvecklingsstadier. Mogna oocyter uppvisade högt uttryck av WNT-blockerare och betakatenin-nedbrytningskomplex, vilket undertrycker signalen före befruktning. Efter befruktning och celldelning lättades denna bromsning upp tillfälligt, medan blastocyster visade istället fokus på cellorienterings- och epitelvävnadsorganisering. Denna stadiespecifika omvandling avslöjar att inte enhetlig aktivering utan precis tidssynkronisering styr WNT-vägen. För swine reproductive technology-leverantörer och regionala embryolaboratorier öppnar detaljerna vägen till optimerad in vitro-befruktning och stamcellsapplikationer — insikter som kan påverka klinisk praksis inom två till tre år.
<p>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 characterize WNT pathway dynamics across key stages of pig in vitro development, including immature oocytes (IMO), mature oocytes (MO), zygotes (ZY), cleaved embryos (2-4 cells; CL), and blastocysts (BL). Global analyses revealed major transcriptomic transitions (FDR &lt;0.05; |Fold Change| &gt;= 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 maturation is associated with increased expression of extracellular WNT antagonists and components of the beta-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 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 development. Our findings indicate that precise temporal modulation-rather than uniform activation-of WNT pathway components accompanies the porcine oocyte-to-embryo transition, providing a molecular framework to better understand early developmental regulation and offering insights relevant to reproductive biotechnology and developmental biology.</p>