Reprogramming Of The Histone Modification H3K27me1 During Mouse Preimplantation Embryonic Development

Background&AimsAfter the combination of a sperm and egg to form a zygote,the embryonic genome is going to undergo a series of reprogramming steps.After fertilization,highly differentiated germ cells gradually dedifferentiate into totipotent embryos,and finally implanted into the uterus where each embryo further develop into an individual.This process involves a series of epigenetic changings,such as histone modification and methylation modification.Although the modification maps and regulation mechanism of H3K27me3 have been revealed,the maps and dynamic changes of its precursor H3K27me1 are still unclear.Therefore,our study intends to analyze the modification of H3K27mel during mouse preimplantation embryonic development,and combine multi-omics data to further study the regulatory role of H3K27,so as to further improve the epigenetic modification map and related mechanism research during mammalian embryo development.Methods1.Using mouse embryonic stem cells as tool cells,CUT&RUN library construction was carried out,and the reliability of our CUT&RUN technique was analyzed by correlation and enrichment analysis compared with the sequencing data from GEO database.2.We carried out CUT&RUN library construction on the mice embryos at various developmental stages before implantation,conducted statistical analysis on the biological repetition of the same sample,and further verified the reliability and repeatability of CUT&RUN library through correlation and clustering results.3.We detected the changes of H3K27mel in mice embryos at various stages before implantation by immunofluorescence experiments.4.We analyzed the modification pattern and profiling of H3K27me1 through data analysis and visual display.5.Combined with the published datas of mouse embryos,we explored the relationship between H3K27mel and transcription.6.Combined with the published transcriptome data and other histone modification data in the database,and further through multi-omics analysis,we explored the regulatory role of H3K27me1 and various epigenetics on embryonic development.Results1.The library data obtained by our laboratory’s CUT&RUN technique was consistent with the published ChIP-seq data,indicated that our CUT&RUN technique was feasible and reliable.2.The biological correlation and cluster analysis showed that the CUT&RUN technique was reproducible,and there were differences between the enrichment of H3K27mel in mES and mouse embryos.With the development of cleavage stage,H3K27me1 modification decreased and reconstructed.3.During the early embryonic development of mice,H3K27me1 was strongly reprogrammed in the gene body at the eight-cell stage,and this situation was independent of gene expression levels.4.H3K27mel was mainly distributed in the hypermethylated gene body regions of oocytes before reprogramming,while it was mainly enriched in the hypomethylated regions after then.5.The overall expression of H3K27 methyltransferase was higher than that of demethylase.6.According to the results of multi-omics analysis,H3K27me1 had a mutually exclusive relationship with H3K27me3 modification,and had a colocalization relationship with H3K36me and H3K4me3.But after H3K27mel reprogramming,the colocalization relationship between H3K27me1 and H3K36me3 disappeared.ConclusionsDuring mouse preimplantation embryo development,H3K27mel reprogramed in the gene body,independent of gene expression levels.Moreover,H3K27me1 colocalized with H3K36me3,but this relationship disappeared after H3K27me1 reprogramming.