11:40-11:50 Comparison of histone H3K4me3 between IVF and ICSI technologies and between boy and girl offspring

Assisted reproductive technology (ART) occur at a critical window of embryo development, overlapping with extensive and sensitive epigenetic reprogramming. The epigenetic changes occur during embryo development may maintain into adulthood. It has been reported offspring conceived via ART have a three times higher risk of epigenetic diseases than naturally conceived children. Nevertheless, investigations into ART-associated epigenetic alteration and sex differences of epigenetic alteration in ART offspring remain limited. Tri-methylated histone H3 lysine-4 (H3K4me3), acetylated histone H3 lysine-9 (H3K9ac), and acetylated histone H3 lysine-27 (H3K27ac) levels were analyzed in human full-term placental tissues from natural pregnancies (n = 27), in vitro fertilization (IVF)-conceived pregnancies (n = 5), and intra-cytoplasmic sperm injection (ICSI)-conceived pregnancies (n = 8) via immunohistochemistry (IHC). Based on H3K4me3 ChIP-sequenced data of newborn cord blood mononuclear cell from naturally-conceived-offspring, IVF-offspring, and ICSI-offspring from NCBI Gene Expression Omnibus (GEO) database, sex-stratified differential peak analysis was carried out using ‘EdgeR’ package. The potential regulators of H3K4me3 were predicated by transcription factor analysis using 'RcisTarget' package and then validated by IHC and siRNA experiments. Meanwhile, to explore the environmental influence on H3K4me3 modification, HTR-8/SVNeo cells were treated with different oxygen conditions, and protein levels of H3K4me3 and the regulators were checked by western blots. We found that placentae from ICSI, but not IVF, showed global H3K4me3 alteration compared to those from natural conception. However, H3K9ac and H3K27ac showed no significant differences between groups. Sex-stratified differential peak analysis demonstrated that, compared with the same-gender naturally-conceived-offspring, ICSI-boys presented more genes with differentially enriched H3K4me3 in promoter region (n = 198) than ICSI-girls (n = 79), IVF-girls (n = 5), and IVF-boys (n = 2). We also found that RNA polymerase II subunit A (Polr2A) knockdown, lysine demethylase 5A (KDM5A) knockdown, and varying oxygen conditions impacted the enrichment of H3K4me3 in HTR-8/SVNeo cells. These findings revealed the differential H3K4me3 modification between IVF- and ICSI-derived offspring and between offspring of different sexes, providing greater insight into ART-associated epigenetic alteration.