Project description:The CpG island methylator phenotype (CIMP) is associated with prognosis and drug sensitivity in multiple cancer types. In gastric cancer, the CIMP is closely associated with Epstein-Barr virus (EBV) infection and AT-rich interactive domain 1A (ARID1A) mutations, a component of the SWI/SNF chromatin remodeling complex. However, the involvement of SWI/SNF defects in CIMP induction has been unclear. In this study, we demonstrate a causal role of ARID1A loss-of-function in CIMP induction. Mutations of SWI/SNF components, especially ARID1A, was associated with the CIMP, as well as EBV infection, in gastric cancers, and also in uterine endometrial and colorectal cancers, which are not affected by EBV infection. Genome-wide DNA methylation analysis showed that ARID1A knockout (KO) in cultured 293FT cells and gastric epithelial cells, GES1, induced aberrant DNA methylation of a substantial number of CpG sites. DNA methylation was induced at genomic regions with high levels of pre-existing histone H3 lysine 27 trimethylation (H3K27me3) and those with acquired H3K27me3 by ARID1A KO. These results showed that the ARID1A mutation induced aberrant DNA methylation, and this is likely to be one of the potential mechanisms of CIMP induction. (See GSE188293 for data of GES1 with ARID1A KO.)
Project description:To investigate whether rat adult hepatocytes would exhibit different characteristics dependent on their ploidy statuses, we compared the transcriptome profile of 2c, 4c and 8c hepatocytes by mRNA microarray.
Project description:DNA methylation at 5-position of cytosine (5mC) is one of the best studied epigenetic modifications that plays important roles in diverse biological processes. Iterative oxidation of 5mC by the Ten-eleven translocation (Tet) family of proteins generates 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxylcytosine (5caC), which can be further processed by DNA repair proteins leading to DNA demethylation. Functional characterization of the Tet proteins has been complicated by the redundancy between the three Tet proteins. Using the CRISPR/Cas9 technology, we have generated mouse embryonic stem cells (ESCs) deficient for all three Tet proteins (TKO). Whole genome bisulphite sequencing (WGBS) analysis revealed that Tet-mediated DNA demethylation mainly occurs distal enhancers as well as promoters that significantly overlap with 5hmC, 5fC and 5caC. Characterization of the Tet TKO ESCs revealed a function for Tet proteins in cell fate restriction as Tet TKO ESCs tend to adopt both primed pluripotent stem cell-like state and 2-cell embryo-like state. In addition, Tet TKO ESCs exhibit elongated telomeres. Thus, our study reveals a role of Tet proteins not only in DNA demethylation, but also in cell fate restriction and telomere maintenance. 2 samples for WGBS and 2 samples for RNA-seq
Project description:DNA methylation at 5-position of cytosine (5mC) is one of the best studied epigenetic modifications that plays important roles in diverse biological processes. Iterative oxidation of 5mC by the Ten-eleven translocation (Tet) family of proteins generates 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxylcytosine (5caC), which can be further processed by DNA repair proteins leading to DNA demethylation. Functional characterization of the Tet proteins has been complicated by the redundancy between the three Tet proteins. Using the CRISPR/Cas9 technology, we have generated mouse embryonic stem cells (ESCs) deficient for all three Tet proteins (TKO). Whole genome bisulphite sequencing (WGBS) analysis revealed that Tet-mediated DNA demethylation mainly occurs distal enhancers as well as promoters that significantly overlap with 5hmC, 5fC and 5caC. Characterization of the Tet TKO ESCs revealed a function for Tet proteins in cell fate restriction as Tet TKO ESCs tend to adopt both primed pluripotent stem cell-like state and 2-cell embryo-like state. In addition, Tet TKO ESCs exhibit elongated telomeres. Thus, our study reveals a role of Tet proteins not only in DNA demethylation, but also in cell fate restriction and telomere maintenance.
Project description:The TET family of dioxygenases catalyze conversion of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), but their involvement in establishing normal 5mC patterns during mammalian development and their contributions to aberrant control of 5mC during cellular transformation remains largely unknown. We depleted TET1, TET2, and TET3 by siRNA in a pluripotent embryonic carcinoma cell model and examined the impact on genome-wide 5mC and 5hmC patterns. TET1 depletion yielded widespread reduction of 5hmC, while depletion of TET2 and TET3 reduced 5hmC at a subset of TET1 targets suggesting functional co-dependence. TET2 or TET3-depletion also caused increased 5hmC, suggesting they play a major role in 5hmC removal. All TETs prevent hypermethylation throughout the genome, a finding dramatically illustrated in CpG island shores, where TET depletion resulted in prolific hypermethylation. Surprisingly, TETs also promote methylation, as hypomethylation was associated with 5hmC reduction. TET function was highly specific to chromatin environment: 5hmC maintenance by all TETs occurred at polycomb-marked chromatin and genes expressed at moderate levels; 5hmC removal by TET2 is associated with highly transcribed genes enriched for H3K4me3 and H3K36me3. Importantly, genes prone to hypermethylation in cancer become depleted of 5hmC with TET deficiency, suggesting the TETs normally promote 5hmC at these loci, and all three TETs are required for 5hmC enrichment at enhancers, a condition necessary for expression of adjacent genes. These results provide novel insight into the division of labor among TET proteins and reveal an important connection of TET activity with chromatin landscape and gene expression. Methylation and hydroxymethylation profiling by affinity-based high throughput sequencing
Project description:The TET family of dioxygenases catalyze conversion of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), but their involvement in establishing normal 5mC patterns during mammalian development and their contributions to aberrant control of 5mC during cellular transformation remains largely unknown. We depleted TET1, TET2, and TET3 by siRNA in a pluripotent embryonic carcinoma cell model and examined the impact on genome-wide 5mC and 5hmC patterns. TET1 depletion yielded widespread reduction of 5hmC, while depletion of TET2 and TET3 reduced 5hmC at a subset of TET1 targets suggesting functional co-dependence. TET2 or TET3-depletion also caused increased 5hmC, suggesting they play a major role in 5hmC removal. All TETs prevent hypermethylation throughout the genome, a finding dramatically illustrated in CpG island shores, where TET depletion resulted in prolific hypermethylation. Surprisingly, TETs also promote methylation, as hypomethylation was associated with 5hmC reduction. TET function was highly specific to chromatin environment: 5hmC maintenance by all TETs occurred at polycomb-marked chromatin and genes expressed at moderate levels; 5hmC removal by TET2 is associated with highly transcribed genes enriched for H3K4me3 and H3K36me3. Importantly, genes prone to hypermethylation in cancer become depleted of 5hmC with TET deficiency, suggesting the TETs normally promote 5hmC at these loci, and all three TETs are required for 5hmC enrichment at enhancers, a condition necessary for expression of adjacent genes. These results provide novel insight into the division of labor among TET proteins and reveal an important connection of TET activity with chromatin landscape and gene expression. Affymetrix gene expression Human ST1.0 microarray of NCCIT human embryonic carcinoma cells (4 samples in duplicate).
Project description:We generated tetracycline-inducible myc-GABPα-expressing Gabpα conditional knockout embryonic stem cells (Tet-Gabbpα cKO ES cells), and then compared the transcriptional profiles between control (-Tet) and Gabpα-null (+Tet) cells by an oligo DNA microarray analysis.