A novel BRAT1–BRP1 complex recognizes histone acetylation and mediates active DNA demethylation and transcriptional activation in Arabidopsis [BS-Seq]
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ABSTRACT: Active DNA demethylation is an important epigenetic phenomenon in many eukaryotes. In Arabidopsis thaliana, ROS1, a 5-methylcytosine DNA glycosylase, is responsible for active DNA demethylation via a base excision repair process. Here, we found that Bromodomain and ATPase domain-containing protein 1 (BRAT1) associates with BRP1 (BRAT1 Partner 1) and forms a tight BRAT1–BRP1 complex required for DNA demethylation. To identify hypermethylated loci at the whole-genome level in brat1, brp1, and ros1, we performed whole-genome bisulfite sequencing.
Project description:Active DNA demethylation is an important epigenetic phenomenon in many eukaryotes. In Arabidopsis thaliana, ROS1, a 5-methylcytosine DNA glycosylase, is responsible for active DNA demethylation via a base excision repair process. Here, we found that Bromodomain and ATPase domain-containing protein 1 (BRAT1) associates with BRP1 (BRAT1 Partner 1) and forms a tight BRAT1–BRP1 complex required for DNA demethylation. To identify hypermethylated loci at the whole-genome level in brat1, brp1, and ros1, we performed whole-genome bisulfite sequencing. Compare the DNA methylation profiles of 10-day old seedlings materials of mutants (brat1, brp1, and ros1) to wild type by whole-genome bisulfite sequencing.
Project description:TET enzymes mediate DNA demethylation by oxidizing 5-methylcytosine (5mC) in DNA to 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC). Because these oxidized methylcytosines (oxi-mC) are not recognized by the maintenance methyltransferase DNMT1, DNA demethylation can occur through “passive”, replication-dependent dilution as cells divide. A distinct, replication-independent (“active”) mechanism of DNA demethylation involves excision of 5fC and 5caC by the DNA repair enzyme thymine DNA glycosylase (TDG), followed by base excision repair. Here we used inducible gene-disrupted mice to show that TET enzymes influence both replication-dependent primary T cell differentiation and replication-independent macrophage differentiation, whereas TDG has no effect. Mice with long-term (1 year) deletion of Tdg are healthy and show normal survival and hematopoiesis. In summary, TET enzymes regulate differentiation and DNA demethylation primarily through passive dilution of oxidized methylcytosines in replicating T cells, and active, replication-independent DNA demethylation mediated by TDG does not appear to be essential for immune cell activation or differentiation.
Project description:The 5-methylcytosine DNA glycosylase/lyase REPRESSOR OF SILENCING 1 (ROS1)-mediated active DNA demethylation is critical for shaping the genomic DNA methylation landscape in Arabidopsis. Whether and how the stability of ROS1 may be regulated by post-translational modifications is unknown. Using a methylation-sensitive PCR (CHOP-PCR)-based forward genetic screen for Arabidopsis DNA hypermethylation mutants, we identified the SUMO E3 ligase SIZ1 as a critical regulator of active DNA demethylation. Dysfunction of SIZ1 leads to hyper-methylation at approximately one thousand genomic regions. SIZ1 physically interacts with ROS1 and mediates the SUMOylation of ROS1. The SUMOylation of ROS1 is reduced in siz1 mutant plants. Compared to that in wild type plants, the protein level of ROS1 is significantly decreased, even though there is an increased level of ROS1 transcripts in siz1 mutant plants. Our results suggest that SIZ1 positively regulates active DNA demethylation by promoting the stability of ROS1 protein through SUMOylation.
Project description:Active DNA demethylation in mammals involves TET-mediated iterative oxidation of 5-methylcytosine (5mC)/5-hydroxymethylcytosine (5hmC) and subsequent excision repair of highly oxidized cytosine bases 5-formylcytosine (5fC)/5-carboxylcytosine (5caC) by Thymine DNA glycosylase (TDG). However, quantitative and high-resolution analysis of active DNA demethylation activity remains challenging. Here we describe M.SssI methylase-assisted bisulfite sequencing (MAB-seq), a method that directly maps 5fC/5caC at single-base resolution. Genome-wide MAB-seq allows systematic identification of 5fC/5caC in Tdg-depleted embryonic stem cells, thereby generating a base-resolution map of active DNA demethylome. A comparison of 5fC/5caC and 5hmC distribution maps indicates that catalytic processivity of TET enzymes correlates with local chromatin accessibility. MAB-seq also reveals strong strand asymmetry of active demethylation within palindromic CpGs. Integrating MAB-seq with other base-resolution mapping methods enables quantitative measurement of cytosine modification states at key transitioning steps of active demethylation pathway, and reveals a regulatory role of 5fC/5caC excision repair in active DNA demethylation cascade. Analysis of 5fC/5caC excision repair-dependent active DNA demethylome by MAB-seq in mouse embryonic stem cells.
Project description:Active DNA demethylation in mammals involves TET-mediated iterative oxidation of 5-methylcytosine (5mC)/5-hydroxymethylcytosine (5hmC) and subsequent excision repair of highly oxidized cytosine bases 5-formylcytosine (5fC)/5-carboxylcytosine (5caC) by Thymine DNA glycosylase (TDG). However, quantitative and high-resolution analysis of active DNA demethylation activity remains challenging. Here we describe M.SssI methylase-assisted bisulfite sequencing (MAB-seq), a method that directly maps 5fC/5caC at single-base resolution. Genome-wide MAB-seq allows systematic identification of 5fC/5caC in Tdg-depleted embryonic stem cells, thereby generating a base-resolution map of active DNA demethylome. A comparison of 5fC/5caC and 5hmC distribution maps indicates that catalytic processivity of TET enzymes correlates with local chromatin accessibility. MAB-seq also reveals strong strand asymmetry of active demethylation within palindromic CpGs. Integrating MAB-seq with other base-resolution mapping methods enables quantitative measurement of cytosine modification states at key transitioning steps of active demethylation pathway, and reveals a regulatory role of 5fC/5caC excision repair in active DNA demethylation cascade.
Project description:TET enzymes mediate DNA demethylation by oxidizing 5-methylcytosine (5mC) in DNA to 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC). Because these oxidized methylcytosines (oxi-mC) are not recognized by the maintenance methyltransferase DNMT1, DNA demethylation can occur through “passive”, replication-dependent dilution as cells divide. A distinct, replication-independent (“active”) mechanism of DNA demethylation involves excision of 5fC and 5caC by the DNA repair enzyme thymine DNA glycosylase (TDG), followed by base excision repair. Here we used inducible gene-disrupted mice to show that TET enzymes influence both replication-dependent primary T cell differentiation and replication-independent macrophage differentiation, whereas TDG has no effect. Mice with long-term (1 year) deletion of Tdg are healthy and show normal survival and hematopoiesis. In summary, TET enzymes regulate differentiation and DNA demethylation primarily through passive dilution of oxidized methylcytosines in replicating T cells, and active, replication-independent DNA demethylation mediated by TDG does not appear to be essential for immune cell activation or differentiation.
Project description:TET enzymes mediate DNA demethylation by oxidizing 5-methylcytosine (5mC) in DNA to 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC). Because these oxidized methylcytosines (oxi-mC) are not recognized by the maintenance methyltransferase DNMT1, DNA demethylation can occur through “passive”, replication-dependent dilution as cells divide. A distinct, replication-independent (“active”) mechanism of DNA demethylation involves excision of 5fC and 5caC by the DNA repair enzyme thymine DNA glycosylase (TDG), followed by base excision repair. Here we used inducible gene-disrupted mice to show that TET enzymes influence both replication-dependent primary T cell differentiation and replication-independent macrophage differentiation, whereas TDG has no effect. Mice with long-term (1 year) deletion of Tdg are healthy and show normal survival and hematopoiesis. In summary, TET enzymes regulate differentiation and DNA demethylation primarily through passive dilution of oxidized methylcytosines in replicating T cells, and active, replication-independent DNA demethylation mediated by TDG does not appear to be essential for immune cell activation or differentiation.
Project description:DNA methylation is an epigenetic mechanism that plays important roles in gene regulation and transposon silencing. Active DNA demethylation has evolved to counterbalance DNA methylation at many endogenous loci. Here, we report that active DNA demethylation also targets viral DNAs, tomato yellow leaf curl China virus (TYLCCNV) and its satellite tomato yellow leaf curl China betasatellite (TYLCCNB), to promote their virulence. We demonstrate that the βC1 protein, encoded by TYLCCNB, interacts with a ROS1-like DNA glycosylase in Nicotiana benthamiana and with the DEMETER (DME) DNA glycosylase in Arabidopsis thaliana. The interaction between βC1 and DME facilitates the DNA glycosylase activity to decrease viral DNA methylation and promote viral virulence. These findings reveal that active DNA demethylation can be regulated by a viral protein to subvert DNA methylation-mediated defense.
Project description:The epigenomes of mammalian sperm and oocytes, characterized by gamete-specific 5-methylcytosine (5mC) patterns, are reprogrammed during early embryogenesis to establish full developmental potential. Previous studies have suggested that the paternal genome is actively demethylated in the zygote while the maternal genome undergoes subsequent passive demethylation via DNA replication during cleavage. Active demethylation is known to depend on 5mC oxidation by Tet dioxygenases and excision of oxidized bases by thymine DNA glycosylase (TDG). Here we show that both maternal and paternal genomes undergo widespread active and passive demethylation in zygotes before the first mitotic division. Passive demethylation was blocked by the replication inhibitor aphidicolin, and active demethylation was abrogated by deletion of Tet3 in both pronuclei. At actively demethylated loci, 5mCs were processed to unmodified cytosines. Surprisingly, the demethylation process was unaffected by the deletion of TDG from the zygote, suggesting the existence of other demethylation mechanisms downstream of Tet3-mediated oxidation.
Project description:The epigenomes of mammalian sperm and oocytes, characterized by gamete-specific 5-methylcytosine (5mC) patterns, are reprogrammed during early embryogenesis to establish full developmental potential. Previous studies have suggested that the paternal genome is actively demethylated in the zygote while the maternal genome undergoes subsequent passive demethylation via DNA replication during cleavage. Active demethylation is known to depend on 5mC oxidation by Tet dioxygenases and excision of oxidized bases by thymine DNA glycosylase (TDG). Here we show that both maternal and paternal genomes undergo widespread active and passive demethylation in zygotes before the first mitotic division. Passive demethylation was blocked by the replication inhibitor aphidicolin, and active demethylation was abrogated by deletion of Tet3 in both pronuclei. At actively demethylated loci, 5mCs were processed to unmodified cytosines. Surprisingly, the demethylation process was unaffected by the deletion of TDG from the zygote, suggesting the existence of other demethylation mechanisms downstream of Tet3-mediated oxidation. The dataset includes RRBS anlysis of 2 MII oocyte samples, 3 WT female pronuclei samples PN3-4 stage, 2 Tet3 KO female pronuclei samples and 2 Aphidicolin treated female pronuclei samples. Also as male counterpart, a Sperm sample, 2 WT male pronuclei samples PN3-4 stage, 2 Tet3 KO male pronuclei samples and 2 Aphidicolin treated male pronuclei samples were included.