The histone lysine demethylase KDM7A is required for normal development and first cell lineage specification in porcine embryos

Abstract

ABSTRACTThere is growing evidence that histone lysine demethylases (KDMs) play critical roles in the regulation of embryo development. This study investigated if KDM7A, a lysine demethylase known to act on mono-(me1) and di-(me2) methylation of H3K9 and H3K27, participates in the regulation of early embryo development. Knockdown of KDM7A mRNA reduced blastocyst formation by 69.2% in in vitro fertilized (IVF), 48.4% in parthenogenetically activated (PA), and 48.1% in somatic cell nuclear transfer (SCNT) embryos compared to controls. Global immunofluorescence (IF) signal in KDM7A knockdown compared to control embryos was increased for H3K27me1 on D7, for H3K27me2 on D3 and D5, for H3K9me1 on D5 and D7, and for H3K9me2 on D5 embryos, but decreased for H3K9me1, me2 and me3 on D3. Moreover, KDM7A knockdown altered mRNA expression, including the downregulation of KDM3C on D3, NANOG on D5 and D7, and OCT4 on D7 embryos, and the upregulation of CDX2, KDM4B and KDM6B on D5 embryos. On D3 and D5 embryos, total cell number and mRNA expression of embryo genome activation (EGA) markers (EIF1AX and PPP1R15B) were not affected by KDM7A knockdown. However, the ratio of inner cell mass (ICM)/total number of cells in D7 blastocysts was reduced by 45.5% in KDM7A knockdown compared to control embryos. These findings support a critical role for KDM7A in the regulation of early development and cell lineage specification in porcine embryos, which is likely mediated through the modulation of H3K9me1/me2 and H3K27me1/me2 levels, and changes in the expression of other KDMs and pluripotency genes.