Identifying division symmetry of mouse embryonic stem cells: negative impact of DNA methyltransferases on symmetric self-renewal

Summary Cell division is a process by which a mother cell divides into genetically identical sister cells, although sister cells often display considerable diversity. In this report, over 350 sister embryonic stem cells (ESCs) were isolated through a microdissection method, and then expression levels of 48 key genes were examined for each sister cell. Our system revealed considerable diversities between sister ESCs at both pluripotent and differentiated states, whereas the similarity between sister ESCs was significantly elevated in a 2i (MEK and GSK3b inhibitors) condition, which is believed to mimic the ground state of pluripotency. DNA methyltransferase 3a/3b were downregulated in 2i-grown ESCs, and the loss of DNA methyltransferases was sufficient to generate nearly identical sister cells. These results suggest that DNA methylation is a major cause of the diversity between sister cells at the pluripotent states, and thus demethylation per se plays an important role in promoting ESC’s self-renewal.
Graphical Abstract
Highlights • ESC division symmetry was characterized through high-throughput RNA analyses • Pluripotent ESCs displayed considerable gene expression diversity between sister cells • Similarity between sister ESCs is significantly elevated at ground-state pluripotency
Jasnos et al. evaluated the division symmetry of murine embryonic stem cells (ESCs) through high-throughput RT-PCR analyses using isolated single sister cells. Results suggest that ESC divisions are not entirely symmetric when they are cultured with LIF and BMP4 only, but a 2i condition significantly promotes symmetric divisions. Analyses of mutant ESCs suggest that DNA demethylation plays an important role in promoting ESC’s self-renewal.