Effect of TSIX disruption on XIST expression in male ES cells.
XIST and its antisense partner, TSIX, encode non-coding RNAs and play key roles in X chromosome inactivation. Targeted disruption of TSIX causes ectopic expression of XIST in the extraembryonic tissues upon maternal transmission, which subsequently results in embryonic lethality due to inactivation of both X chromosomes in females and a single X chromosome in males. TSIX, therefore, plays a crucial role in maintaining the silenced state of XIST in CIS and regulates the imprinted X inactivation in the extraembryonic tissues. In this study, we examined the effect of TSIX disruption on XIST expression in the embryonic lineage using embryonic stem (ES) cells as a model system. Upon differentiation, XIST is ectopically activated in a subset of the nuclei of male ES cells harboring the TSIX-deficient X chromosome. Such ectopic expression, however, eventually ceased during prolonged culture. It is likely that surveillance by the X chromosome counting mechanism somehow shuts off the ectopic expression of XIST before inactivation of the X chromosome.
Sado
T
T
Division of Human Genetics, National Institute of Genetics, The Graduate University for Advanced Studies, Mishima, Japan. tsado@lab.nig.ac.jp
Li
E
E
Sasaki
H
H
D000818:Animals; D002460:Cell Line; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism*; D005786:Gene Expression Regulation; D017404:In Situ Hybridization, Fluorescence / Q000379:methods; D008297:Male; D051379:Mice; D009154:Mutation; D012313:RNA / Q000235:genetics / Q000378:metabolism; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics*
D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D014157:Transcription Factors; C465658:Tsix transcript, mouse; C077885:XIST non-coding RNA; D012313:RNA