Goldman M A, Reeves P S, Wirth C M, Zupko W J, Wong M A, Edelhoff S, Disteche C M
Department of Biology, San Francisco State University, CA 94132-1722, USA.
Chromosome Res. 1998 Aug;6(5):397-404. doi: 10.1023/a:1009229423535.
We analyzed an X-linked metallothionein-vasopressin (MTVP) fusion transgene that undergoes X-chromosome inactivation (X inactivation) and an X-linked transferrin (TFN) transgene that escapes X inactivation with respect to methylation in the 5' regulatory regions. The MTVP transgene promoter region is unmethylated when the transgene is on the active X chromosome and methylated when on the inactive X chromosome. Interestingly, the MTVP transgene is not detectably transcribed from the male X chromosome, although it is unmethylated, consistent with its availability for transcription. The TFN transgene promoter region is hypomethylated on both the active and inactive X chromosomes, consistent with its expression from both chromosomes. The TFN and MTVP transgenes have been mapped to chromosomal regions D and C, respectively, by fluorescence in situ hybridization. These observations are discussed in the context of our understanding of the role of DNA methylation in the spread and maintenance of X-chromosome inactivation.
我们分析了一个经历X染色体失活（X inactivation）的X连锁金属硫蛋白-血管加压素（MTVP）融合转基因，以及一个在5'调控区域甲基化方面逃避X染色体失活的X连锁转铁蛋白（TFN）转基因。当转基因位于活性X染色体上时，MTVP转基因启动子区域未甲基化，而位于失活X染色体上时则甲基化。有趣的是，尽管MTVP转基因未甲基化，但其在雄性X染色体上未检测到可转录情况，这与其可用于转录的情况相符。TFN转基因启动子区域在活性和失活X染色体上均为低甲基化，这与其在两条染色体上的表达情况相符。通过荧光原位杂交，TFN和MTVP转基因已分别定位到染色体区域D和C。我们结合对DNA甲基化在X染色体失活的传播和维持中所起作用的理解来讨论这些观察结果。
