Project description:In this study, we investigated the dynamics during differentiation of the in vivo binding sites of ZBTB2, a putative reader for unmethylated DNA. We performed DNA pull-downs followed by mass spectrometry, using a genomic sequence containing either unmethylated or methylated CpGs, to study the influence of DNA methylation on ZBTB2 binding. Additionally, we performed interaction proteomics to identify ZBTB2 interaction partners. We found that ZBTB2 recruits a zinc finger module of three proteins to unmethylated DNA.
Project description:Gene methylation profiling of immortalized human mesenchymal stem cells comparing HPV E6/E7-transfected MSCs cells with human telomerase reverse transcriptase (hTERT)- and HPV E6/E7-transfected MSCs. hTERT may increase gene methylation in MSCs. Goal was to determine the effects of different transfected genes on global gene methylation in MSCs.
Project description:The inverse correlation between DNA methylation and steady state mRNA levels is imperfect; a large number of genes, which are unmethylated in the promoter region, are silenced. We show here that either pharmacological inhibition of DNA methyltransferase (DNMT1) with 5-aza-2'-deoxycytidine (5-azaCdR) or knockdown with shRNA dramatically expands the number of transcription initiation positions in the genome including many unmethylated promoters. Induction of unmethylated promoters in response to inhibition of DNMT1 is a result of activation by demethylation of methylated upstream regulators such as the transcription factor HNF4A. Our results imply that the landscape of genes that are regulated by DNA methylation is more wide-ranging than genes silenced by methylation of their own cis regulatory sequences. We propose a hierarchical model of transcriptional control by DNA methylation whereby regulation of unmethylated promoters is dependent on the methylation state of trans upstream regulators.
Project description:The inverse correlation between DNA methylation and steady state mRNA levels is imperfect; a large number of genes, which are unmethylated in the promoter region, are silenced. We show here that either pharmacological inhibition of DNA methyltransferase (DNMT1) with 5-aza-2'-deoxycytidine (5-azaCdR) or knockdown with shRNA dramatically expands the number of transcription initiation positions in the genome including many unmethylated promoters. Induction of unmethylated promoters in response to inhibition of DNMT1 is a result of activation by demethylation of methylated upstream regulators such as the transcription factor HNF4A. Our results imply that the landscape of genes that are regulated by DNA methylation is more wide-ranging than genes silenced by methylation of their own cis regulatory sequences. We propose a hierarchical model of transcriptional control by DNA methylation whereby regulation of unmethylated promoters is dependent on the methylation state of trans upstream regulators.
Project description:The inverse correlation between DNA methylation and steady state mRNA levels is imperfect; a large number of genes, which are unmethylated in the promoter region, are silenced. We show here that either pharmacological inhibition of DNA methyltransferase (DNMT1) with 5-aza-2'-deoxycytidine (5-azaCdR) or knockdown with shRNA dramatically expands the number of transcription initiation positions in the genome including many unmethylated promoters. Induction of unmethylated promoters in response to inhibition of DNMT1 is a result of activation by demethylation of methylated upstream regulators such as the transcription factor HNF4A. Our results imply that the landscape of genes that are regulated by DNA methylation is more wide-ranging than genes silenced by methylation of their own cis regulatory sequences. We propose a hierarchical model of transcriptional control by DNA methylation whereby regulation of unmethylated promoters is dependent on the methylation state of trans upstream regulators.
Project description:Methylation of DNA at CpG dinucleotides represents one of the most important epigenetic mechanisms involved in the control of gene expression in vertebrate cells. In this report, we conducted high-throughput nucleosome reconstitution experiments on 572 KB of human DNA and 668 KB of mouse DNA that was unmethylated or methylated in order to investigate the effects of this epigenetic modification on the positioning and stability of nucleosomes. The DNA loci from both species contained the genes that encode the serum albumin family, the MYC protein, and the tumor suppressor p53. The results demonstrated that a small subset of nucleosomes positioned by nucleotide sequence was sensitive to methylation where the modification increased the affinity of these sequences for the histone octamer. The features that distinguished these nucleosomes from the bulk of the methylation-insensitive nucleosomes were an increase in the frequency of CpG dinucleotides and a unique rotational orientation of CpGs such that their minor grooves tended to face toward the histones in the nucleosome rather than away. We propose that these features serve to enhance the affinity of methylated DNA for the histone octamer and that this effect could be involved in gene regulatory mechanisms such as silencing. These methylation-sensitive nucleosomes were preferentially associated with exons as compared to introns while unmethylated CpG islands near transcription start sites became enriched in nucleosomes upon methylation. The results of this study suggest that the effects of DNA methylation on nucleosome stability in vitro can recapitulate what has been observed in the cell and provide a direct link between DNA methylation and the structure and function of chromatin. For the human data, there were 3 unmethylated nucleosome replicates, 2 methylated nucleosome replicates, an unmethylated MNase control, and an unmethylated sonicated control. For the mouse data, there were 2 unmethylated nucleosome replicates, 2 methylated nucleosome replicates, an unmethylated MNase control, a methylated MNase control, and an unmethylated sonicated control.