Histone Demethylase <i>KDM4D</i> Could Improve the Developmental Competence of Buffalo (<i>Bubalus Bubalis</i>) Somatic Cell Nuclear Transfer (SCNT) Embryos

<jats:title>Abstract</jats:title><jats:p>Somatic cell nuclear transfer (SCNT) holds vast potential in agriculture. However, its applications are still limited by its low efficiency. Histone 3 lysine 9 trimethylation (H3K9me3) was identified as an epigenetic barrier for this. Histone demethylase <jats:italic>KDM4D</jats:italic> could regulate the level of H3K9me3. However, its effects on buffalo SCNT embryos are still unclear. Thus, we performed this study to explore the effects and underlying mechanism of <jats:italic>KDM4D</jats:italic> on buffalo SCNT embryos. The results revealed that compared with the IVF embryos, the expression level of <jats:italic>KDM4D</jats:italic> in SCNT embryos was significantly lower at 8- and 16-cell stage, while the level of H3K9me3 in SCNT embryos was significantly higher at 2-cell, 8-cell, and blastocyst stage. Microinjection of <jats:italic>KDM4D</jats:italic> mRNA could promote the developmental ability of buffalo SCNT embryos. Furthermore, the expression level of ZGA-related genes such as <jats:italic>ZSCAN5B</jats:italic>, <jats:italic>SNAI1</jats:italic>, <jats:italic>eIF-3a</jats:italic>, and <jats:italic>TRC</jats:italic> at the 8-cell stage was significantly increased. Meanwhile, the pluripotency-related genes like <jats:italic>POU5F1</jats:italic>, <jats:italic>SOX2</jats:italic>, and <jats:italic>NANOG</jats:italic> were also significantly promoted at the blastocyst stage. The results were reversed after <jats:italic>KDM4D</jats:italic> was inhibited. Altogether, these results revealed that <jats:italic>KDM4D</jats:italic> could correct the H3K9me3 level, increase the expression level of ZGA and pluripotency-related genes, and finally, promote the developmental competence of buffalo SCNT embryos.</jats:p>