Unveiling the effects of regulating endogenous growth factors and apoptosis via DGCR8 on yak blastocyst formation

DiGeorge syndrome critical region gene 8 (DGCR8), a key regulator of mammalian miRNA synthesis, influences early embryonic development. To clarify its role in yak embryos, we generated embryos by in vitro fertilization and microinjected DGCR8-specific inhibitors at 12 h post-fertilization to knock down DGCR8 mRNA (DGCR8-KD group), while the control group received an equal volume of saline. Embryonic developmental competence was assessed, and mRNA expression levels of DGCR8, EGF, IGF-1, BAX, and BCL-2 were measured at multiple stages using qRT-PCR. In a rescue group (DGCR8-KD + GF), 100 ng mL^-1 EGF and 100 ng mL^-1 IGF-1 were added after knockdown, following our team's previous protocol. DGCR8 mRNA expression was high in 2-, 4-, and 8-cell yak embryos and significantly decreased in the morula and blastocyst stages (P < 0.05). DGCR8 knockdown markedly reduced the morula/blastocyst development rate and TE/ICM cell numbers (P < 0.05), whereas exogenous growth factors restored these impairments (P < 0.05). In DGCR8-KD embryos, EGF and IGF-1 mRNA/protein levels declined, BAX (pro-apoptotic) increased, and BCL-2 (anti-apoptotic) decreased relative to controls; supplementation reversed these expression patterns. Thus, DGCR8 functions predominantly in 2-8-cell pre-implantation embryos, regulating endogenous growth factors and apoptosis-related factors to support morula/blastocyst formation. Exogenous EGF/IGF-1 alleviates DGCR8 deficiency, providing insight into its role in mammalian early embryogenesis.