|
|
|
|
|
|
|
||
Article |
X chromosome choice occurs independently of asynchronous replication timing
Correspondence to R. Jaenisch: jaenisch{at}wi.mit.edu
In mammals, dosage compensation is achieved by X chromosome inactivation in female cells. Xist is required and sufficient for X inactivation, and Xist gene deletions result in completely skewed X inactivation. In this work, we analyzed skewing of X inactivation in mice with an Xist deletion encompassing sequence 5 KB upstream of the promoter through exon 3. We found that this mutation results in primary nonrandom X inactivation in which the wild-type X chromosome is always chosen for inactivation. To understand the molecular mechanisms that affect choice, we analyzed the role of replication timing in X inactivation choice. We found that the two Xist alleles and all regions tested on the X chromosome replicate asynchronously before the start of X inactivation. However, analysis of replication timing in cell lines with skewed X inactivation showed no preference for one of the two Xist alleles to replicate early in S-phase before the onset of X inactivation, indicating that asynchronous replication timing does not play a role in skewing of X inactivation.
J. Gribnau's and K. Monkhorst's present address is Dept. of Cell Biology, Erasmus MC, 3015 GE Rotterdam, Netherlands.
Abbreviations used in this paper: cas, castaneus; dpc, days past coitum; ES, embryonic stem; MEF, mouse embryonic fibroblast; SD, single-double; Xa, active X; Xce, X controlling element; Xi, inactive X; Xic, X inactivation center.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
