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Nature 461, 1007-1012 (2009); doi:10.1038/nature08456. In this Letter, we claimed that hormone-regulated transcriptional control involves DNA demethylation mediated by MBD4. Subsequently, we corrected some figure panels that appeared to have [...]

Epigenetic modifications at the histone level affect gene regulation in response to extracellular signals. However, regulated epigenetic modifications at the DNA level, especially active DNA demethylation, in gene activation are not well understood. Here we report that DNA methylation/demethylation is hormonally switched to control transcription of the cytochrome p450 27B1 (CYP27B1) gene. Reflecting vitamin-D-mediated transrepression of the CYP27B1 gene by the negative vitamin D response element (nVDRE), methylation of CpG sites (5mCpG) is induced by vitamin D in this gene promoter. Conversely, treatment with parathyroid hormone, a hormone known to activate the CYP27B1 gene, induces active demethylation of the 5mCpG sites in this promoter. Biochemical purification of a complex associated with the nVDRE-binding protein (VDIR, also known as TCF3) identified two DNA methyltransferases, DNMT1 and DNMT3B, for methylation of CpG sites, as well as a DNA glycosylase, MBD4 (ref. 10). Protein-kinase-C-phosphorylated MBD4 by parathyroid hormone stimulation promotes incision of methylated DNA through glycosylase activity, and a base-excision repair process seems to complete DNA demethylation in the MBD4-bound promoter. Such parathyroid-hormone-induced DNA demethylation and subsequent transcriptional derepression are impaired in Mbd4-/- mice. Thus, the present findings suggest that methylation switching at the DNA level contributes to the hormonal control of transcription. [ABSTRACT FROM AUTHOR]

Abstract: Vitamin D receptor (VDR) mediates a wide variety of vitamin D actions through transcriptional controls of target genes as a ligand-dependent transcription factor. The transactivation by VDR is known to associate with two co-activator complexes, DRIP/TRAP and p160/CBP, through physical interaction with DRIP205 and p160 members (TIF2) components, respectively. However, functional difference between the two co-activator complexes for VDR co-activation remains unclear. In the present study, to address this issue, a series of point mutants in VDR helix 12 were generated to test the functional association. Alanine replacement of VDR valine 418 resulted in loss of DRIP205 interaction, but it was still transcriptionally potent with ability to interact with TIF2. Surprisingly, the V421A mutant was only partially impaired in transactivation without co-activator interaction, implying presence of a putative co-activator/complex. Thus, these findings suggest that ligand-induced transcriptional controls by VDR require a number of known and unknown co-regulator complexes, that may support the tissue-specific function of VDR. [Copyright &y& Elsevier]

Estrogen exerts its diverse effects through two subtypes of estrogen receptors (ER), ERalpha and ERbeta. Each subtype has its own distinct function and expression pattern in its target tissues. Little, however, is known about the transcriptional regulatory mechanism of ERbeta in the major ERbeta-expressing tissues. Using biochemical methods, we identified and described a novel ERbeta coactivator. This protein, designated GIOT-4, was biochemically purified from 293F cells. It coactivated ERbeta in ovarian granulosa cells. GIOT-4 expression was induced by stimulation with follicle-stimulating hormone (FSH). GIOT-4 recruited an SWI/SNF-type complex in a ligand-independent manner to ERbeta as an ER subtype-specific physical bridging factor and induced subsequent histone modifications in the ERbeta target gene promoters in a human ovarian granulosa cell line (KGN). Indeed, two ERbeta-specific target genes were upregulated by FSH at a specific stage of a normal ovulatory cycle in intact mice. These findings imply the presence of a novel regulatory convergence between the gonadotropin signaling cascade and ERbeta-mediated transcription in the ovary.

The female sex steroid hormone oestrogen stimulates both cell proliferation and cell differentiation in target tissues. These biological actions are mediated primarily through nuclear oestrogen receptors (ERs). The ligand-dependent transactivation of ERs requires several nuclear co-regulator complexes; however, the cell-cycle-dependent associations of these complexes are poorly understood. By using a synchronization system, we found that the transactivation function of ERalpha at G2/M was lowered. Biochemical approaches showed that ERalpha associated with two discrete classes of ATP-dependent chromatin-remodelling complex in a cell-cycle-dependent manner. The components of the NuRD-type complex were identified as G2/M-phase-specific ERalpha co-repressors. Thus, our results indicate that the transactivation function of ERalpha is cell-cycle dependent and is coupled with a cell-cycle-dependent association of chromatin-remodelling complexes.