Wolf S F, Migeon B R
Nature. 1982 Feb 25;295(5851):667-71. doi: 10.1038/295667a0.
Studies of methylation along 28 kilobases of X-chromosome DNA, assayed by Southern blot analysis using cloned X-chromosome-specific probes, indicates that X DNA methylation in normal human cells changes with replication, is not correlated with number of X chromosomes or transcriptional activity, and is less stable and more prevalent than when the human X is in the foreign environment of mouse-human hybrid cells. In contrast with observations of others in heteroploid cells, we observed no derepression of the inactive X in clonal populations of normal human fibroblasts treated with 5-azacytidine. This may reflect the differences in stability of the methylation of the human X in a foreign environment. Our observations preclude ubiquitous methylation differences as the molecular basis for X-chromosome inactivation.
利用克隆的X染色体特异性探针通过Southern印迹分析对沿X染色体DNA的28千碱基的甲基化研究表明，正常人细胞中的X DNA甲基化随复制而变化，与X染色体数量或转录活性无关，并且与人类X处于小鼠 - 人类杂交细胞的外来环境中时相比，其稳定性更低且更普遍。与在异倍体细胞中其他人的观察结果相反，我们在用5-氮杂胞苷处理的正常人成纤维细胞克隆群体中未观察到失活X的去抑制。这可能反映了人类X在外来环境中甲基化稳定性的差异。我们的观察结果排除了普遍存在的甲基化差异作为X染色体失活的分子基础。
