Project description:Eukaryotic genomes are heavily regulated by epigenetic marks that often act to modulate the transcriptional control of genetic elements. In Arabidopsis thaliana the ATXR5 and ATXR6 histone methyltransferases, and their cognate H3K27 monomethylation mark, act in transcriptional silencing while also maintaining genome stability by preventing generation of excess DNA corresponding to pericentromeric heterochromatin. In this study we characterize the atxr5 atxr6 transcriptome and its relationship to the DNA damage response which suggests that the atxr5 atxr6 transcriptional defects may be epistatic to the genome instability defects in the mutants. In addition we isolate several factors that modulate both the transcriptional and genomic instability phenotypes of atxr5 atxr6 mutants, which suggest a mechanism for atxr5 atxr6-induced extra DNA involving conflicts between the replicative and transcriptional processes in the cell.
Project description:Eukaryotic genomes are heavily regulated by epigenetic marks that often act to modulate the transcriptional control of genetic elements. In Arabidopsis thaliana the ATXR5 and ATXR6 histone methyltransferases, and their cognate H3K27 monomethylation mark, act in transcriptional silencing while also maintaining genome stability by preventing generation of excess DNA corresponding to pericentromeric heterochromatin. In this study we characterize the atxr5 atxr6 transcriptome and its relationship to the DNA damage response which suggests that the atxr5 atxr6 transcriptional defects may be epistatic to the genome instability defects in the mutants. In addition we isolate several factors that modulate both the transcriptional and genomic instability phenotypes of atxr5 atxr6 mutants, which suggest a mechanism for atxr5 atxr6-induced extra DNA involving conflicts between the replicative and transcriptional processes in the cell. PolyA RNA sequencing (RNA-seq), whole-genome resequencing (DNA-seq), and whole-genome bisulfite sequencing (methyl-seq) was performed on Arabidospsis thaliana mutant and wildtype plants. DNA-seq was used to characterize DNA copy number and map EMS-induced mutations, RNA-seq was used to quantify transcript abundance and map EMS-induced mutations, and methyl-seq was used to assess DNA methylation. Details of the relationship between samples in this series and figures in the associated manuscript can be found in Supplemental Table 4 of the associated manuscript. Unless otherwise noted in the description all lines are ecotype Columbia, and all genotypes should be assumed homozygous unless otherwise indicated with a '/'.
Project description:The SET-domain protein SUVR5 mediates H3K9me2 deposition and silencing at stimulus response genes in a DNA methylation independent manner [SELEX]
Project description:The SET-domain protein SUVR5 mediates H3K9me2 deposition and silencing at stimulus response genes in a DNA methylation independent manner [ChIP-chip]
Project description:The SET-domain protein SUVR5 mediates H3K9me2 deposition and silencing at stimulus response genes in a DNA methylation independent manner [RNA-Seq]
Project description:The regulation of gene expression is controlled in part by post-translational modifications to histone proteins. Methylation at histone H3, lysine 27 (H3K27), which is catalyzed by Polycomb repressive complex 2 (PRC2), is associated with silenced chromatin. Previous studies have identified dysregulation of H3K27 methylation in pediatric diffuse intrinsic pontine gliomas (DIPGs), the majority of which feature mutation of lysine 27 to methionine. This “oncohistone” potently inhibits PRC2 activity and leads to a global reduction in H3K27 methylation. Similar to DIPG, posterior fossa type A (PFA) ependymomas also show low levels of H3K27 methylation. Although PFAs do not possess the H3K27M oncohistone mutation, they do show increased expression of Cxorf67. Interestingly, Cxorf67 contains a C-terminal sequence that resembles the sequence surrounding H3K27, and we find that this portion of Cxorf67 inhibits PRC2 activity to an even greater extent than the H3K27M oncohistone. Thus, we suggest re-naming Cxorf67 as EZHIP (Enhancer of Zeste Homologs Inhibitory Protein). Furthermore, when expressed in 293T cells, Cxorf67 interacts with several members of PRC2 and induces changes in H3K27 methylation patterns that mirror the changes in H3K27 methylation induced by expression of H3K27M. We propose that PFAs have dysregulated H3K27 methylation by a mechanism that involves inhibition of PRC2 by Cxorf67, which could drive tumorigenesis.
Project description:We investigated EZH2 binding in the presence and absence of MMSET protein. MMSET overexpression in t(4;14)+ myeloma leads to global loss of H3K27 methylation and redistribution of EZH2 binding throughout the genome ChIP-seq for EZH2 in two cell types