REGULATION OF X-CHROMOSOME EXPRESSION IN MAMMALS

X在早期胚胎发育过程中失活的启动及其机制 在整个发育过程中保持不活动的X状态 是X失活过程中的中心问题。这些功能和 卵子发生过程中的后续重新激活是独特的发育变化 它产生了整个X染色体的协调调节。 这一建议是研究X失活的一种广泛的方法 在鼠标中进行处理。我们的实验策略借鉴了使用 X染色体基因变异我们已经从广泛的样本中恢复 小鼠基因库跟踪特定X染色体的表达。我们 已经将这一策略扩展到识别DNA变异，可以使用 跟踪活跃和非活跃X染色体基因上的DNA甲基化。我们 现在能够扩展我们对自然发生的变异的使用 用X染色体基因高效筛选诱变剂处理过的股票 额外的X染色体标记，并识别提供 对X染色体调控进行遗传分析的机会 失活过程。 我们还扩大了X染色体基因的生化标记的使用 检测X染色体基因在X；常染色体中的表达 易位。近端或近端基因的表达 移位的远端将提供对该部位的一些洞察(S) 在失活过程中确定X染色体的身份。这 提案还描述了研究X染色体再激活的实验 胚胎癌细胞-体细胞杂交。这项工作将提供 有关停用和重新激活过程的重要信息以及 它提供了一个机会来开发新的实验方法来研究 X染色体调控。

The initiation of X inactivation during early embryogenesis and the subsequent maintenance of the inactive X condition throughout development are central issues in the X-inactivation process. These features and the succeeding reactivation during oogenesis are unique developmental changes which produce the coordinate regulation of an entire X chromosome. This proposal is a broadly based approach to studying the X-inactivation process in the mouse. Our experimental strategies draw upon using X-chromosome gene variation we have recovered from a wide sampling of the mouse gene pool to follow the expression of specific X chromosomes. We have extended this strategy to identifying DNA variation which can be used to follow DNA methylation on active and inactive X-chromosome genes. We are now in a position to extend our use of naturally occurring variation of X chromosome genes to efficiently screen mutagen treated stocks for additional X chromosome markers and to identify mutations which provide an opportunity to pursue a genetic analysis of X-chromosome regulation during the inactivation process. We are also extending the use of biochemical markers of X-chromosome genes to examine the expression of X-chromosome genes in X;autosome translocations. The expression of genes which are either proximal or distal to the translocation will provide some insight into the site(s) which establish X-chromosome identity in the inactivation process. This proposal also describes experiments to study X-chromosome reactivation in embryonal carcinoma cell-somatic cell hybrids. This work will provide important information about the inactivation and reactivation process and it offers an opportunity to develop new experimental approaches to studying X-chromosome regulation.