P-115 GATAD2B is required for pre-implantation embryo development by delaying zygotic genome activation

Abstract

Abstract Study question Major zygotic genome activation (ZGA) involving the activation of thousands of genes occurs at the late-2cell stage, but the regulatory mechanisms governing ZGA remain unclear. Summary answer Our results demonstrate that GATAD2B is essential for early embryonic development, in part through facilitating zygotic genome activation (ZGA). What is known already Acetylation modifications of histone tails promote transcriptional activation, and the maternal deletion of H4K16ac leads to failure in ZGA. GATAD2B is one of the core subunits of the Nucleosome remodeling and histone deacetylation complex(NuRD). Study design, size, duration Using mouse embryos as the research model, the study was conducted over a period of approximately two years to ensure a relatively small-scale investigation. Participants/materials, setting, methods We examined the dynamic expression of NURD complex components, including GATAD2B, during pre-implantation embryonic stages. GATAD2B expression was specifically reduced via microinjection of GATAD2B-siRNA during the zygote stage, revealing its impact on early embryonic development in mice. Zygotic genome activation (ZGA), morula compaction, and blastocyst lineage differentiation were investigated using immunofluorescence, western blot, and other techniques. Additionally, we employed RNA-seq, protein immunoprecipitation, and mass spectrometry to uncover underlying molecular mechanisms. Main results and the role of chance Our research has shown that GATAD2B exhibits specific nucleus localization and high protein expression from the late-2-cell to 8-cell. This intriguing phenomenon prompted us to investigate the relationship between GATAD2B and the ZGA. We discovered a distinctive pattern of GATAD2B, starting from the late 2-cell stage with nuclear localization. GATAD2B depletion resulted in defective embryonic development, including increased DNA damage at morula, decreased blastocyst formation rate and abnormal differentiation of ICM/TE lineages. Consistent with the delay during the cleavage stage, the transcriptome analysis of the 2-cell revealed inhibition of the cell cycle G2/M phase transition pathway. Furthermore, the GATAD2B proteomics data provided clear evidence of a certain association between GATAD2B and molecules involved in the cell cycle pathway. As hypothesized, GATAD2B-deficient 2-cell embryos exhibited abnormalities in ZGA during the maternal-to-embryonic transition, with lower expression of the major ZGA mark MERVL. Limitations, reasons for caution Given the limitations of antibody effectiveness and specificity required for the experiments, the exploration of molecular mechanisms is still ongoing. Wider implications of the findings Our findings have elucidated the impact of GATAD2B on early embryonic development through the regulation of zygotic genome activation (ZGA), providing a novel genetic explanation for clinical defects in early embryonic development. Trial registration number not applicable