title: XIST repression in the absence of DNMT1 and DNMT3B.
abstract: X chromosome inactivation (XCI) in human and mice involves XIST/Xist gene expression from the inactive X (Xi) and repression from the active X (Xa). Repression of the XIST/Xist gene on the Xa has been associated with methylation of its 5' region. In mice, Dnmt1 has been shown to be involved in the methylation and transcriptional repression of Xist on Xa. We examined maintenance of XIST gene repression on Xa in HCT116 cell lines knockout for either DNMT1 or DNMT3B and for DNMT1 and DNMT3B simultaneously. Methylation of the XIST promoter and XIST transcriptional repression is sustained in DNMT1-, DNMT3B- and DNMT1/DNMT3B knockout cells. Despite global DNA demethylation, the double knockout cells present only partial demethylation of the XIST promoter, which is not sufficient for gene reactivation. In contrast, global DNA demethylation with 5-aza-2'-deoxycytidine leads to XIST expression. Therefore, in these human cells maintenance of XIST methylation is controlled differently than global genomic methylation and in the absence of both DNMT1 and DNMT3B.
authors.affiliation: Depto Biologia and Centro de Estudos do Genoma Humano, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Luciana R
authors.initials: LR
authors.lastname: Vasques
authors.forename: Raquel
authors.initials: R
authors.lastname: Stabellini
authors.forename: Fei
authors.initials: F
authors.lastname: Xue
authors.forename: X Cindy
authors.initials: XC
authors.lastname: Tian
authors.forename: Marina
authors.initials: M
authors.lastname: Soukoyan
authors.forename: Lygia V
authors.initials: LV
authors.lastname: Pereira
mesh_terms: D002460:Cell Line; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics / Q000378:metabolism*; D019175:DNA Methylation; D006801:Humans; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated / Q000235:genetics / Q000378:metabolism*; D000097584:DNA Methyltransferase 3B
chemical_list: D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D000097584:DNA Methyltransferase 3B; C077885:XIST non-coding RNA; C000619380:DNMT1 protein, human; C000619381:Dnmt1 protein, mouse