Overexpression of BRG1 improves early development of porcine somatic cell nuclear transfer embryos

Abstract

The epigenetic modification levels of donor cells directly affect the developmental potential of somatic cell nuclear transfer (SCNT) embryos. BRG1, as an epigenetic modifying enzyme, has not yet been studied in donor cells and SCNT embryos. In this study, BRG1 was overexpressed in porcine fetal fibroblasts (PFFs), its effect on chromatin openness and gene transcription was examined, subsequently, the development potential of porcine SCNT embryos was investigated. The results showed that compared with the control group, the percentage of G1 phase cells was significantly increased (32.3 % ± 0.87 vs 25.7 % ± 0.81, P < 0.05) in the experimental group. The qRT-PCR results showed that the expression of H3K9me3-related genes was significantly decreased (P < 0.05), HAT1 was significantly increased (P < 0.05). Assay of Transposase Accessible Chromatin sequencing (ATAC-seq) results revealed that SMARCA4、NANOG、SOX2、MAP2K6 and HIF1A loci had more open chromatin peaks in the experimental group. The RNA-seq results showed that the upregulated genes were mainly enriched in PI3K/AKT and WNT signaling pathways, and the downregulated genes were largely focused on disease development. Interestingly, the developmental rate of porcine SCNT embryos was improved (27.33 % ± 1.40 vs 17.83 % ± 2.02, P < 0.05), the expression of zygotic gene activation-related genes in 4-cell embryos, and embryonic development-related genes in blastocysts was significantly upregulated in the experimental group (P < 0.05). These results suggest that overexpression of BRG1 in donor cells is benefit for the developmental potential of porcine SCNT embryos.