Synergism of Xist RNA, DNA methylation, and histone hypoacetylation in maintaining X chromosome inactivation.

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Csankovszki G, Nagy A, Jaenisch R

Synergism of Xist RNA, DNA methylation, and histone hypoacetylation in maintaining X chromosome inactivation.

J Cell Biol. 2001 May 14;153(4):773-84.

PubMed ID

11352938 [ View in PubMed

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Abstract

Xist RNA expression, methylation of CpG islands, and hypoacetylation of histone H4 are distinguishing features of inactive X chromatin. Here, we show that these silencing mechanisms act synergistically to maintain the inactive state. Xist RNA has been shown to be essential for initiation of X inactivation, but not required for maintenance. We have developed a system in which the reactivation frequency of individual X-linked genes can be assessed quantitatively. Using a conditional mutant Xist allele, we provide direct evidence for that loss of Xist RNA destabilizes the inactive state in somatic cells, leading to an increased reactivation frequency of an X-linked GFP transgene and of the endogenous hypoxanthine phosphoribosyl transferase (Hprt) gene in mouse embryonic fibroblasts. Demethylation of DNA, using 5-azadC or by introducing a mutation in Dnmt1, and inhibition of histone hypoacetylation using trichostatin A further increases reactivation in Xist mutant fibroblasts, indicating a synergistic interaction of X chromosome silencing mechanisms.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Decitabine	DNA (cytosine-5)-methyltransferase 1	Protein	Humans	Yes	Inhibitor	Details