G-Quadruplex stabilization impairs early embryo development by impairing DNA replication and inducing R-loops and DNA damage accumulation.

In brief: G-Quadruplex ligands-induced stabilization of G4 impairs DNA replication and promotes R-loops accumulation, leading to elevated double-strand breaks, and ultimately early embryo arrest. Abstract: DNA damage or replication impairment can lead to developmental arrest of embryos. To ensure the smooth progression of early embryo development, precise genomic regulation is crucial. Among the regulatory elements of genomic integrity, G-quadruplex (G4), as an important non-B-type DNA structure, is widely present in the genome and participates in gene expression regulation. However, the role of G4 structures in early embryonic development remain unclear. Here, we investigated the effect and mechanisms of G4 stabilization by G4 ligands, pyridostatin, and Braco-19, on early mouse embryonic development. Our results show that G4 ligands treatment-induced excessive G4 stabilization leads to disrupted DNA replication, and transcription-replication conflicts contribute to elevated R-loop signals, causing an increase in double-strand breaks, thereby causing early embryo arrest. These findings highlight the critical role of DNA G4 structures in early embryo cleavage.