Visualization of inactive X chromosome in preimplantation embryos utilizing MacroH2A-EGFP transgenic mouse.
One of the two X chromosomes is inactivated in female eutherian mammals. MacroH2A, an unusual histone variant, is known to accumulate on the inactive X chromosome (Xi) during early embryo development, and can thus be used as a marker of the Xi. In this study, we produced a transgenic mouse line expressing the mouse MacroH2A1.2-enhanced green fluorescent protein (EGFP) fusion protein (MacroH2A-EGFP) under the control of a CAG promoter and verified whether MacroH2A-EGFP would be useful for tracing the process of X chromosome inactivation by visualizing Xi noninvasively in preimplantation embryos. In transgenic female mice, MacroH2A-EGFP formed a fluorescent focus in nuclei throughout the body. In female blastocysts, the MacroH2A-EGFP focus colocalized with Xist RNA, well known as a marker of Xi. Fluorescence marking of Xi was first observed in some embryonic cells between the 4- and 8-cell stages. These results demonstrate that MacroH2A can bind to the Xi by around the 8-cell stage in female mouse embryos. These MacroH2A-EGFP transgenic mice might be useful to elucidate the process of X chromosome inactivation during the mouse life cycle.
Division of Molecular Biology, School of Life Sciences, Faculty of Medicine, Tottori University, Yonago, Tottori, 683-8503, Japan.
Atsumi
A
Soma
Kenzo
K
Sato
Tomoko
T
Nakanishi
D000818:Animals; D001755:Blastocyst / Q000378:metabolism*; D005260:Female; D018703:Founder Effect; D049452:Green Fluorescent Proteins / Q000235:genetics*; D006657:Histones / Q000235:genetics*; D051379:Mice; D008822:Mice, Transgenic; D008856:Microscopy, Fluorescence; D019076:Transgenes / Q000235:genetics; D014960:X Chromosome / Q000235:genetics; D049951:X Chromosome Inactivation
D006657:Histones; D049452:Green Fluorescent Proteins