Chromosome X Dosage Modulates Development of Aneuploidy in Genetically Diverse Mouse Embryonic Stem Cells

The genetic integrity of pluripotent stem cells (PSC) is integral to their applications in research and therapy, but it is compromised by frequent development of copy number variations. Little is known about the basis of the variable genomic integrity among different PSC lines. Here we identify aneuploidies using RNA-seq and proteomics data from a panel of mouse embryonic stem cell (mESC) lines derived from 170 Diversity Outbred mice. We identified 62 lines with detectable aneuploid subpopulations and a subset of originally XX lines that lost one Chromosome X (XO). Strikingly, a much lower proportion of XX lines were aneuploid, compared to XY or XO lines. Two single-cell RNA-seq data sets demonstrated that aneuploid XY DO mESC also show lower Chromosome X gene expression and that XY mESC accumulate higher aneuploid proportions in culture than isogenic XX lines. Possible mechanisms for this protective effect of X chromosome dosage include our discovery that the lines with two active X Chromosomes have a higher expression of 2-cell-like state genes, and differential expression of X-linked tumor suppressor genes associated with DNA damage response. ### Competing Interest Statement The authors have declared no competing interest.