IDH2 and GLUD1 depletion arrests embryonic development through an H4K20me3 epigenetic barrier in porcine parthenogenetic embryos

Isocitrate dehydrogenase 2 (IDH2) and glutamate dehydrogenase 1 (GLUD1) are key enzymes involved in the production of α-ketoglutarate (α-KG), a metabolite central to the tricarboxylic acid cycle and glutamine metabolism. In this study, we investigated the impact of IDH2 and GLUD1 on early porcine embryonic development following IDH2 and GLUD1 knockdown (KD) via double-stranded RNA (dsRNA) microinjection. Results showed that KD reduced α-KG levels, leading to delayed embryonic development, decreased blastocyst formation, increased apoptosis, reduced blastomere proliferation, and pluripotency. Additionally, IDH2 and GLUD1 KD induced abnormally high levels of trimethylation of lysine 20 of histone H4 (H4K20me3) at the 4-cell stage, likely resulting in transcriptional repression of embryonic genome activation (EGA)-related genes. Notably, KD of lysine methyltransferase 5C (KMT5C) and supplementation with exogenous α-KG reduced H4K20me3 expression and partially rescued these defects, suggesting a critical role of IDH2 and GLUD1 in the epigenetic regulation and proper development of porcine embryos. Overall, this study highlights the significance of IDH2 and GLUD1 in maintaining normal embryonic development through their influence on α-KG production and subsequent epigenetic modifications.