Affiliation:
1. Department of Cell Biology
2. Department of Reproduction and Development, Erasmus MC-University Medical Center, Rotterdam, The Netherlands
Abstract
ABSTRACT
In mammalian female cells, one X chromosome is inactivated to prevent a dose difference in the expression of X-encoded proteins between males and females.
Xist
RNA, required for X chromosome inactivation, is transcribed from the future inactivated X chromosome (Xi), where it spreads in
cis
, to initiate silencing. We have analyzed
Xist
RNA transcription and localization throughout the cell cycle. It was found that
Xist
transcription is constant and that the mature RNA remains attached to the Xi throughout mitosis. Diploid and tetraploid cell lines with an MS2-tagged
Xist
gene were used to investigate spreading of
Xist
. Most XXXX
MS2
tetraploid mouse embryonic stem (ES) cells inactivate the X
MS2
chromosome and one other X chromosome. Analysis of cells with two Xi's indicates that
Xist
RNA is retained by the Xi of its origin and does not spread in
trans
. Also, in XX
MS2
diploid mouse ES cells with an autosomal
Xist
transgene, there is no
trans
exchange of
Xist
RNA from the Xi to the autosome. We propose that
Xist
RNA does not dissociate from the Xi of its origin, which precludes a model of diffusion-mediated
trans
spreading of
Xist
RNA.
Publisher
American Society for Microbiology
Subject
Cell Biology,Molecular Biology
Cited by
68 articles.
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