Brief suppression of SUMOylation in embryonic stem cells generates embryo-like structures

Recent advances in synthetic mammalian embryo models have opened new avenues to understand the complex events controlling lineage specification and morphogenetic processes occurring during peri-implantation and early organogenesis. Two main strategies have been developed to build embryo-like structures (ELSs): by assembling extraembryonic and embryonic stem cells (ESCs) or by subjecting ESCs to various morphogens. Here, we show that mouse ESCs solely exposed to chemical inhibition of SUMOylation, a post-translational modification which acts as a general chromatin barrier to cell fate transitions, generates ELSs comprising both anterior neural and trunk-associated regions. HypoSUMOylation-instructed ESCs first give rise to adherent spheroids which, once in suspension, self-organize into gastrulating structures containing cell types spatially and functionally related to embryonic and extraembryonic compartments. Alternatively, spheroids cultured in an optimized droplet-microfluidic device form elongated structures that undergo axial organization reminiscent of natural embryo morphogenesis. Single-cell RNA-sequencing further revealed a variety of cellular lineages including properly positioned anterior neuronal cell types, Schwann cell precursors and paraxial mesoderm segmented into somite-like structures. Mechanistically, transient SUMOylation suppression gradually increases DNA methylation genome-wide and repressive marks deposition at Nanog, enhancing ESC plasticity. Our approach provides a proof of principle for a potential strategy to study early embryogenesis by targeting molecular roadblocks of cell fate change to shape multicellular architecture.