Effects of cytochalasin B on DNA methylation and histone modification in parthenogenetically activated porcine embryos

DNA methylation and histone modification play important roles in the development of mammalian embryos. Cytochalasin B (CB) is an actin polymerization inhibitor that can significantly affect cell activity and is often used in studies concerning cytology. In recent years, CB is also commonly being used inin vitroexperiments on mammalian embryos, but few studies have addressed the effect of CB on the epigenetic modification of embryonic development, and the mechanism underlying this process is also unknown. This study was conducted to investigate the effects of CB on DNA methylation and histone modification in the development of parthenogenetically activated porcine embryos. Treatment with 5 μg/mL CB for 4 h significantly increased the cleavage rate, blastocyst rate and total cell number of blastocysts. However, the percentage of apoptotic cells and the expression levels of the apoptosis-related genesBCL-XL,BAXandCASP3were significantly decreased. Treatment with CB significantly decreased the expression levels ofDNMT1,DNMT3a,DNMT3b,HAT1andHDAC1at the pronuclear stage and promoted the conversion of 5-methylcytosine (5mC) into 5-hydroxymethylcytosine (5hmC). After CB treatment, the level of AcH3K9 was upregulated and the level of H3K9me3 was downregulated. When combined with Scriptaid and 5-Aza-Cdr, CB further improved the embryonic development competence and decreased the expression ofBCL-XL,BAXandCASP3. In conclusion, these results suggest that CB could improve embryonic development and the quality of the blastocyst by improving the epigenetic modification during the development of parthenogenetically activated embryos.