title: Activators and repressors: A balancing act for X-inactivation.
abstract: In early female embryos X-chromosome inactivation occurs concomitant with up regulation of the non-coding RNA, Xist, on the future inactive X-chromosome. Up regulation of Xist and coating of the future inactive X is sufficient to induce silencing. Therefore unlocking the mechanisms of X-chromosome inactivation requires thorough understanding of the transcriptional regulators, both activators and repressors, which control Xist. Mouse pluripotent embryonic stem cells, which have two active X chromosomes, provide a tractable ex vivo model system for studying X-chromosome inactivation, since this process is triggered by differentiation signals in these cultured cells. Yet there are significant discrepancies found between ex vivo analyses in mouse embryonic stem cells and in vivo studies of early embryos. In this review we elaborate on potential models of how Xist is up regulated on a single X chromosome in female cells and how ex vivo and in vivo analyses enlighten our understanding of the activators and repressors that control this non-coding RNA gene.
authors.affiliation: Department of Biochemistry and Biophysics, University of California, San Francisco, 600 16th Street, San Francisco, CA 94158, United States.
authors.forename: Leeanne
authors.initials: L
authors.lastname: Goodrich
authors.affiliation: Department of Biochemistry and Biophysics, University of California, San Francisco, 600 16th Street, San Francisco, CA 94158, United States. Electronic address: barbara.panning@gmail.com.
authors.forename: Barbara
authors.initials: B
authors.lastname: Panning
authors.affiliation: Department of Biochemistry and Biophysics, University of California, San Francisco, 600 16th Street, San Francisco, CA 94158, United States.
authors.forename: Karen Nicole
authors.initials: KN
authors.lastname: Leung
mesh_terms: D000818:Animals; D006801:Humans; D008957:Models, Genetic; D039904:Pluripotent Stem Cells / Q000378:metabolism; D062085:RNA, Long Noncoding / Q000235:genetics / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D049951:X Chromosome Inactivation / Q000235:genetics*
chemical_list: D062085:RNA, Long Noncoding
keywords: Early post-implantation development; Embryonic stem cell; Epiblast stem cell; Non-coding RNA; Pluripotency; Random X-chromosome inactivation; Rlim/Rnf12; Tsix; X-inactivation center; Xist