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

Abstract

There 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.

Histone Lysine Demethylases KDM5B and KDM5C Modulate Genome Activation and Stability in Porcine Embryos

“…After fertilization, a number of epigenetic changes are required to setup and modulate the embryo developmental program. Activation of transcriptional activity, cell lineage commitment and DNA damage repair are among the critical events regulated by epigenetic modifications in early developing embryos (Ostrup et al, 2013;Bohrer et al, 2015;Dahl et al, 2016;Dicks et al, 2017;Ding et al, 2017;Eckersley-Maslin et al, 2018;Rissi et al, 2019). Both maternal and paternal derived chromatins FIGURE 7 | Relative mRNA abundance of KDM5B and KDM5C in embryos exposed (UV+) or not (UV-) to UV radiation for 10 s at 36 h, Day 5 or Day 7 post-PA.…”

“…must be epigenetically programed after fertilization to make embryos capable to pursue their normal developmental course (Siklenka et al, 2015;Dahl et al, 2016;Teperek et al, 2016). A variety of epigenetic regulators such as erasers (e.g., KDM1A, KDM4D, KDM7A) and writers (e.g., SETDB1, SUV39H1/H2, G9a) are necessary to properly implement the epigenetic program in embryos (Jullien et al, 2014;Matoba et al, 2014;Golding et al, 2015;Siklenka et al, 2015;Dahl et al, 2016;Eymery et al, 2016;Zhang et al, 2016;Dumdie et al, 2018;Zylicz et al, 2018;Rissi et al, 2019). However, much remains to be done to uncover the function and interaction of each epigenetic regulator.…”

“…Epigenetic marks regulate crucial events during oocyte to embryo transition (OET) and early embryo development. These include embryo genome activation (EGA), the first cell lineage specification and differentiation, as well as genome repair and stability (Canovas et al, 2012;Bohrer et al, 2014;Ancelin et al, 2016;Dahl et al, 2016;Wasson et al, 2016;Rissi et al, 2019). An epigenetic network is involved in the modulation of mRNA transcription required for normal embryo development (Tadros and Lipshitz, 2009;Ostrup et al, 2013;Eckersley-Maslin et al, 2018).…”

“…An epigenetic network is involved in the modulation of mRNA transcription required for normal embryo development (Tadros and Lipshitz, 2009;Ostrup et al, 2013;Eckersley-Maslin et al, 2018). This includes changes in methylation of DNA and histones, such as methylation of lysine 4 (H3K4me), 9 (H3K9me), and 27 (H3K27me) in the histone H3, which are required for normal embryo transcription and programing cell differentiation (Jullien et al, 2014;Dahl et al, 2016;Zhang et al, 2016;Dumdie et al, 2018;Rissi et al, 2019). Although epigenetic marks can be inherited from the gametes (Siklenka et al, 2015;Teperek et al, 2016), how the epigenetic network is regulated to coordinate the different vital functions in early developing embryos remains not well understood.…”

A Mechanism Leading to Changes in Copy Number Variations Affected by Transcriptional Level Might Be Involved in Evolution, Embryonic Development, Senescence, and Oncogenesis Mediated by Retrotransposons

“…As proteins, such as activation-induced cytidine deaminase and histone lysine demethylase (KDM) could affect demethylation, and the knockdown of KDM7A could seriously influence the development of inner cell mass (ICM) (Rissi and Glanzner, 2019 ), the genes whose CNVs are extended at the beginning of embryogenesis might be related to demethylation. The continuous CNV extension of these genes with the demethylation effect increases their expression, which antagonizes methylation.…”