DNA demethylation in hormone-induced transcriptional derepression

Abstract

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 ((5m)CpG) 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 (5m)CpG 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.

Aldosterone reprograms promoter methylation to regulate αENaC transcription in the collecting cuct

“…The fact that overexpression of MBD4 impaired aldosterone induction of the ␣ENaC promoter (Fig. 6B), indicates that MBD4 is not participating in active DNA demethylation initiated by the deaminase-catalyzed conversion of 5mC to thymine, as has been reported in other systems (10). The results also demonstrate that aldosterone reprogrammed the methylation status of the R3 subregion of the ␣ENaC promoter from a predominance of 5mC under basal conditions to a predominance of 5hmC (Fig.…”

“…Transcription may be limited by an effect of promoter methylation itself to reduce the affinity for trans-activating factors and by methyl-CpG binding domain (MBD) proteins, which recognize 5=-methylated cytosine (5mC) residues, recruiting transcriptional repressors or chromatin modifiers to these sites (16) and stearically hindering transcription factor binding (12). Moreover, DNMT3b and MBD4 have been shown to physically and functionally interact in a complex with negative vitamin D response elementbinding protein to initiate and maintain methylation of the cytochrome P-450 (CYP)27B1 promoter (10).…”

Cell-Specific Polymorphism and Hormonal Regulation of DNA Methylation in Scavenger Receptor Class B, Type I

“…DNA methylation in the promoter region represses gene transcription through inhibition of transcription factor binding or the recruitment of methyl-binding proteins (Robertson and Jones, 2000). DNA methylation was reported to be regulated by hormone treatment (Kim et al, 2009;Lee et al, 2012). We tried to clarify the hormonal regulation of SR-BI expression and DNA methylation.…”

“…In rat granulosa cell, the methylation status of CpG sites in StAR promoter as well as CYP19A1 promoter exhibits polymorphism (Lee et al, 2012). Treatment with parathyroid hormone induces active demethylation of the CpG sites in CYP27B1 gene promoter, whereas the parathyroid hormone was reported to stimulate CYP27B1 expression (Kim et al, 2009).…”

Epigenetic Regulation of Aldosterone Synthase Gene by Sodium and Angiotensin II

“…The methyl‐CpG binding domain (MBD) proteins are capable of directly binding to methylated DNA 5, 6. Methyl‐CpG binding protein 2 (MECP2), MBD1, and MBD2 can repress methylation‐based transcription 7. A non‐CpG island promoter regulates CYP11B2 gene expression.…”