Yen Ziny C, Meyer Irmtraud M, Karalic Sanja, Brown Carolyn J
Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada.
Genomics. 2007 Oct;90(4):453-63. doi: 10.1016/j.ygeno.2007.07.002. Epub 2007 Aug 28.
Mammalian X-chromosome inactivation achieves dosage compensation between the sexes by the silencing of one X chromosome in females. In Eutheria, X inactivation is initiated by the large noncoding RNA Xist; however, it is unknown how this RNA results in silencing of the chromosome or why, at least in humans, many genes escape silencing in somatic cells. We have sequenced the coast mole Xist gene and compared the Xist RNA sequence among seven eutherians to provide insight into the structure of the RNA and origins of the gene. Using DNA methylation of promoter sequences to assess whether genes are silenced in females we report the inactivation status of seven X-linked genes in humans and mice as well as two additional eutherians, the mole and the cow, providing evidence that escape from inactivation is common among Eutheria.
哺乳动物的X染色体失活通过雌性中一条X染色体的沉默来实现两性之间的剂量补偿。在真兽亚纲中，X染色体失活由大型非编码RNA Xist启动；然而，尚不清楚这种RNA如何导致染色体沉默，以及为什么至少在人类中，许多基因在体细胞中逃脱了沉默。我们对海岸鼹鼠的Xist基因进行了测序，并比较了七种真兽亚纲动物的Xist RNA序列，以深入了解该RNA的结构和该基因的起源。利用启动子序列的DNA甲基化来评估基因在雌性中是否沉默，我们报告了人类、小鼠以及另外两种真兽亚纲动物鼹鼠和牛中七个X连锁基因的失活状态，提供了证据表明在真兽亚纲中逃脱失活是常见的。
