Knockdown of Y-box-binding protein 2 induces mitochondrial dysfunction to interrupt zygotic genome activation in porcine embryos

Y-box-binding protein 2 (YBX2) is a germ cell-specific protein that plays important roles in mRNA stability, transcription, and translation. However, the effects of YBX2 on porcine embryos development remain unclear. To investigate the function of YBX2 in early porcine embryonic development, YBX2 knockdown (KD) was performed via siRNA microinjection at the single-cell stage. The expression level of YBX2 gene was measured by quantitative real-time polymerase chain reaction (qRT-PCR). The effect of YBX2 on mitochondrial function and zygotic genome activation were detected by qRT-PCR, western blot, immunofluorescence staining. The results showed that YBX2 is essential for early embryonic development. YBX2 KD decreased the blastocyst rate, mitochondrial activity, and the expression levels of NRF1, NRF2, and SIRT1, thereby reducing mitochondrial biogenesis. In addition, YBX2 KD led to an increase in maternal mRNA levels and a decrease in zygotic genome activation mRNA levels. However, maternal protein levels were reduced, indicating that YBX2 can affect the maternal-to-zygotic transition. Meanwhile, H3K9ac levels decreased and H3K9me3 levels increased following YBX2 KD, suggesting that YBX2 regulates gene transcription. YBX2 affected embryonic development by regulating mitochondrial biogenesis and ZGA expression.