Stage-Specific Profiling of Transforming Growth Factor-β, Fibroblast Growth Factor and Wingless-int Signaling Pathways during Early Embryo Development in The Goat

Objective: This research intends to unravel the temporal expression profiles of genes involved in three developmentally important signaling pathways [transforming growth factor-beta (TGF-beta), fibroblast growth factor (FGF) and wingless/int (WNT)] during pre- and peri-implantation goat embryo development. Materials and Methods: In this experimental study, we examined the transcripts that encoded the ligand, receptor, intracellular signal transducer and modifier, and the downstream effector, for each signaling pathway. In vitro mature MII oocytes and embryos at three distinctive stages [8-16 cell stage, day-7 (D7) blastocysts and day-14 (D14) blastocysts] were separately prepared in triplicate for comparative real-time reverse transcriptase polymerase chain reaction (RT-PCR) using the selected gene sets. Results: Most components of the three signaling pathways were present at more or less stable levels throughout the assessed oocyte and embryo developmental stages. The transcripts for TGF-beta, FGF and WNT signaling pathways were all induced in unfertilized MII-oocytes. However, developing embryos showed gradual patterns of decrease in the activities of TGF-beta, FGF and WNT components with renewal thereafter. Conclusion: The results suggested that TGF-beta, FGF and WNT are maternally active signaling pathways required during earlier, rather than later, stages of pre- and peri-implantation goat embryo development.