α-Ketoglutarate Enhances Epigenetic Remodeling and Developmental Competence in Porcine SCNT Embryos

Incomplete zygotic genome activation (ZGA) is a major barrier limiting the developmental competence of somatic cell nuclear transfer (SCNT) embryos in pigs. α-Ketoglutarate (α-KG), a key metabolic intermediate and cofactor for α-KG-dependent dioxygenases, has been implicated in epigenetic remodeling during early embryogenesis. In this study, we investigated whether α-KG supplementation could improve developmental potential and ZGA-associated events in porcine SCNT embryos. α-KG treatment improved cleavage progression, increased blastocyst formation rates, increased total blastocyst cell number and ICM cell number, and reduced apoptosis and DNA damage. In addition, α-KG improved microtubule organization and actin distribution during early cleavage stages, contributing to more coordinated cell division. Mechanistically, α-KG increased global 5-hydroxymethylcytosine (5hmC) levels and elevated the abundance of activating histone marks, including H3K4me3 and H3K27ac. Expression of several ZGA-associated genes, including DUXA, ZSCAN4, EIF1A, and KLF17, was significantly increased following α-KG supplementation, accompanied by enhanced nascent RNA synthesis. Notably, inhibition of TET enzymes with Bobcat339 attenuated the effects of α-KG on 5hmC accumulation, transcriptional activity, and embryo development. Collectively, these findings indicate that α-KG improves developmental competence and is associated with enhanced epigenetic remodeling in porcine SCNT embryos, at least in part through TET-associated pathways, providing a potential strategy for improving nuclear reprogramming efficiency in animal cloning.