title: Species-specific differences in X chromosome inactivation in mammals.
abstract: In female mammals, the dosage difference in X-linked genes between XX females and XY males is compensated for by inactivating one of the two X chromosomes during early development. Since the discovery of the X inactive-specific transcript (XIST) gene in humans and its subsequent isolation of the mouse homolog, Xist, in the early 1990s, the molecular basis of X chromosome inactivation (X-inactivation) has been more fully elucidated using genetically manipulated mouse embryos and embryonic stem cells. Studies on X-inactivation in other mammals, although limited when compared with those in the mice, have revealed that, while their inactive X chromosome shares many features with those in the mice, there are marked differences in not only some epigenetic modifications of the inactive X chromosome but also when and how X-inactivation is initiated during early embryonic development. Such differences raise the issue about what extent of the molecular basis of X-inactivation in the mice is commonly shared among others. Recognizing similarities and differences in X-inactivation among mammals may provide further insight into our understanding of not only the evolutionary but also the molecular aspects for the mechanism of X-inactivation. Here, we reviewed species-specific differences in X-inactivation and discussed what these differences may reveal.
authors.affiliation: Division of Epigenomics and Development, Medical Institute of Bioregulation, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan. tsado@bioreg.kyushu-u.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Sado
authors.forename: Takehisa
authors.initials: T
authors.lastname: Sakaguchi
mesh_terms: D000818:Animals; D005260:Female; D050172:Genes, X-Linked / Q000235:genetics*; D006801:Humans; D008297:Male; D008322:Mammals / Q000235:genetics*; D051379:Mice; D013045:Species Specificity; D049951:X Chromosome Inactivation / Q000235:genetics*