In mammalian genomes, differentially methylated regions (DMRs) and histone marks including trimethylation of histone 3 lysine 27 (H3K27me3) at imprinted genes are asymmetrically inherited to control parentally-biased gene expression. However, neither parent-of-origin-specific transcription nor imprints have been comprehensively mapped at the blastocyst stage of preimplantation development. Here, we address this by integrating transcriptomic and epigenomic approaches in mouse preimplantation embryos. We find that seventy-one genes exhibit previously unreported parent-of-origin-specific expression in blastocysts (nBiX: novel blastocyst-imprinted expressed). Uniparental expression of nBiX genes disappears soon after implantation. Micro-whole-genome bisulfite sequencing (µWGBS) of individual uniparental blastocysts detects 859 DMRs. We further find that 16% of nBiX genes are associated with a DMR, whereas most are associated with parentally-biased H3K27me3, suggesting a role for Polycomb-mediated imprinting in blastocysts. nBiX genes are clustered: five clusters contained at least one published imprinted gene, and five clusters exclusively contained nBiX genes. These data suggest that early development undergoes a complex program of stage-specific imprinting involving different tiers of regulation.
The authors thank Robert Feil and Anton Wutz for helpful discussions and comments, Samuel Collombet and Peter Fraser for sharing embryo TAD coordinates, and Andy Riddel at the Cambridge Stem Cell Institute and Thomas Sauer at the Max Perutz Laboratories FACS facility for flow-sorting. We thank the team of the Biomedical Sequencing Facility at the CeMM and the Vienna Biocenter Core Facilities (VBCF) for support with next-generation sequencing. We are grateful to animal care teams at the University of Bath and MRC Harwell. A.C.F.P. acknowledges support from the UK Medical Research Council (MR/N000080/1 and MR/N020294/1) and Biotechnology and Biological Sciences Research Council (BB/P009506/1). L.S. is part of the FWF doctoral programme SMICH and supported by an Austrian Academy of Sciences DOC Fellowship. M.L. is funded by a Vienna Research Group for Young Investigators grant (VRG14-006) by the Vienna Science and Technology Fund (WWTF) and by the Austrian Science Fund FWF (I3786 and P31334).
Santini L, Halbritter F, Titz-Teixeira F, et al. Genomic imprinting in mouse blastocysts is predominantly associated with H3K27me3. Nature Communications. 2021;12(1). doi:10.1038/s41467-021-23510-4
Santini, L., Halbritter, F., Titz-Teixeira, F., Suzuki, T., Asami, M., Ma, X., … Leeb, M. (2021). Genomic imprinting in mouse blastocysts is predominantly associated with H3K27me3. Nature Communications. Springer Nature. https://doi.org/10.1038/s41467-021-23510-4
Santini, Laura, Florian Halbritter, Fabian Titz-Teixeira, Toru Suzuki, Maki Asami, Xiaoyan Ma, Julia Ramesmayer, et al. “Genomic Imprinting in Mouse Blastocysts Is Predominantly Associated with H3K27me3.” Nature Communications. Springer Nature, 2021. https://doi.org/10.1038/s41467-021-23510-4.
L. Santini et al., “Genomic imprinting in mouse blastocysts is predominantly associated with H3K27me3,” Nature Communications, vol. 12, no. 1. Springer Nature, 2021.
Santini L, Halbritter F, Titz-Teixeira F, Suzuki T, Asami M, Ma X, Ramesmayer J, Lackner A, Warr N, Pauler F, Hippenmeyer S, Laue E, Farlik M, Bock C, Beyer A, Perry ACF, Leeb M. 2021. Genomic imprinting in mouse blastocysts is predominantly associated with H3K27me3. Nature Communications. 12(1), 3804.
Santini, Laura, et al. “Genomic Imprinting in Mouse Blastocysts Is Predominantly Associated with H3K27me3.” Nature Communications, vol. 12, no. 1, 3804, Springer Nature, 2021, doi:10.1038/s41467-021-23510-4.
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