SP1 controls zygotic genome activation and morula-to-blastocyst transition in mouse embryos

Why clinicians should know about it

• Picked for Embryology (paper of the day, 21 July 2026).

Abstract

Specificity protein 1 (SP1) is the most active member of the specificity protein and Krüppel-like factor (Sp/KLF) family and is widely expressed across all mammalian cell types. However, more detailed studies on the role of SP1 in preimplantation embryonic development are needed. Here, we analyzed the role of SP1 in the development of preimplantation mouse embryos through supplementation with a small molecular inhibitor (plicamycin) and microinjection of Sp1 siRNA. We found that SP1 was indispensable for zygotic genome activation (ZGA) and the morula-to-blastocyst transition. Plicamycin supplementation arrested embryo development at the 2-cell stage and resulted in aberrant RNA polymerase II preconfiguration. Sp1 expression knockdown by Sp1 siRNA microinjection caused most embryos to arrest at the morula stage, and the expression of NANOG, POU5F1 and CDX2 significantly decreased. Both plicamycin supplementation and Sp1 siRNA microinjection decreased embryonic H3K4me3 levels and increased H3K9me3 levels. Moreover, when Sp1 was overexpressed, the embryos were arrested at the 2-cell stage, the H3K4me3 level increased, and the H3K9me3 level decreased. In conclusion, our findings demonstrate that SP1 is crucial for mouse preimplantation embryonic development through the regulation of gene expression and histone modifications.

Abstract as published, via PubMed.