Abstract
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.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Alleles
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Animals
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Cell Line
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Chromosomal Proteins, Non-Histone / genetics
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DNA Replication Timing / genetics*
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DNA-Binding Proteins / genetics
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Dosage Compensation, Genetic*
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Embryo, Mammalian / cytology
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Embryo, Mammalian / metabolism
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Embryonic Development / genetics
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Exons / genetics
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Female
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Flow Cytometry
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Gene Deletion
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Genotype
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Green Fluorescent Proteins / genetics
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Histone Demethylases
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In Situ Hybridization, Fluorescence
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Interleukin-1 Receptor-Associated Kinases
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Male
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Methyl-CpG-Binding Protein 2
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Mice
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Mice, Transgenic
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Oxidoreductases, N-Demethylating
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Protein Kinases / genetics
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Proteins / genetics
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RNA, Long Noncoding
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RNA, Untranslated / genetics
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Repressor Proteins / genetics
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S Phase / genetics
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Stem Cells / physiology
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X Chromosome / genetics*
Substances
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Chromosomal Proteins, Non-Histone
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DNA-Binding Proteins
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Mecp2 protein, mouse
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Methyl-CpG-Binding Protein 2
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Proteins
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RNA, Long Noncoding
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RNA, Untranslated
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Repressor Proteins
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XIST non-coding RNA
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Green Fluorescent Proteins
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Histone Demethylases
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Kdm5c protein, mouse
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Oxidoreductases, N-Demethylating
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Protein Kinases
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Interleukin-1 Receptor-Associated Kinases