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 in- volved in three developmentally important signaling pathways [transforming growth factor-β (TGF-β), fibroblast growth factor (FGF) and wingless/int (WNT)] during preand peri-implan- tation 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 down- stream 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) blas- tocysts] were separately prepared in triplicate for comparative real-time reverse tran- scriptase 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-β, 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-β, FGF and WNT components with renewal thereafter. CONCLUSION The results suggested that TGF-β, FGF and WNT are maternally active signaling pathways required during earlier, rather than later, stages of preand peri- implantation goat embryo development.