Reactivation of the inactive X chromosome through the asymmetric precursor cell division in the embryonal carcinoma cell population

小鼠胚胎干细胞（ES）和胚胎癌细胞（EC）的单细胞来源的细胞群不是同质的：在这些未分化的细胞群中经常出现表型和/或功能异质的细胞。然而，其细胞异质性的机制细节仍然未知。我们研究了失活的X染色体（Xi）在未分化的EC细胞群中是如何被重新激活的，发现（1）干细胞样前体细胞是随机出现在未分化的EC细胞群中的，（2）前体细胞的不对称细胞分裂产生前体细胞和HAT抗性（= Xi-重新激活）细胞。将需要进一步的分析，以澄清收购干细胞样的属性，包括Xi-再激活能力，在不对称细胞分裂的潜在机制。

A single-cell derived cell populations of mouse embryonic stem (ES) and embryonal carcinoma (EC) cell are not homogeneous: heterogeneous cells in phenotype and/or function are frequently appeared in these undifferentiated cell populations. However mechanistic detail of their cellular heterogeneity remains unknown. We investigated how inactive X chromosomes (Xi) are reactivated in the undifferentiated EC cell population, and found that (1) stem-cell-like precursor cells are stochastically appeared in the populations, and (2) asymmetric cell divisions of the precursor cell generates a precursor cell and a HAT resistant (= Xi-reactivated) cell. Further analysis will be needed to clarify the underlying mechanisms for the acquisition of stem-cell-like properties, including Xi-reactivation ability, during asymmetric cell divisions.