Dvash Tamar, Fan Guoping
Department of Human Genetics and the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine, University of California at Los Angeles, 90095, USA.
Epigenetics. 2009 Jan;4(1):19-22. doi: 10.4161/epi.4.1.7438. Epub 2009 Jan 17.
X chromosome inactivation (XCI) allows dosage compensation of the expression from sex chromosome in mammalian female cells. Although this mechanism is extensively studied in the mouse model organism, the corresponding mechanism during human development is largely unknown. The generation of human embryonic stem cells (hESCs) provides an invaluable tool to address early embryogenesis in humans. Even though hESCs were supposed to shed light on the XCI process in early human embryogenesis, previous studies largely indicated inconsistency in the status of XCI in these cells. Recently, new data suggested that in vitro culture might affect epigenetic mechanisms such as XCI. In this review we will present the existing data regarding XCI variations in hESC as compared to data from the mouse embryo and embryonic stem cells. We will also suggest possible explanations for the conflicting observations in the literature regarding XCI in hESCs.
X染色体失活（XCI）可实现哺乳动物雌性细胞中性染色体表达的剂量补偿。尽管在小鼠模式生物中对该机制进行了广泛研究，但人类发育过程中的相应机制在很大程度上仍不清楚。人类胚胎干细胞（hESC）的产生为研究人类早期胚胎发育提供了一个极其宝贵的工具。尽管hESC本应有助于阐明人类早期胚胎发育中的XCI过程，但先前的研究在很大程度上表明这些细胞中XCI的状态不一致。最近，新数据表明体外培养可能会影响诸如XCI等表观遗传机制。在本综述中，我们将呈现与小鼠胚胎和胚胎干细胞数据相比，关于hESC中XCI变异的现有数据。我们还将对文献中关于hESC中XCI的相互矛盾的观察结果提出可能的解释。
