Project description:To gain genome wide information on the association of EZH2 with promoter regions in HeLa cells, DamID experiments and subsequent analysis by promoter arrays (Affymetrix GeneChip Human Promoter 1.0R ) were performed. The DamID method uses fusions of the bacterial Dam DNA methylase and the protein of interest, to direct the enzymatic activity to the proteinM-bM-^@M-^Ys genomic binding sites, where the DNA is methylated. Methylated DNA is then extracted, enriched and further analysed by microarray. EZH2 is the enzymatic subunit of the Polycomb Repressive Complex 2, which deposits the H3K27me3 mark on chromatin. This mark is associated with low gene expression, either in polycomb repressed regions or, in combination with methylation of H3K4, at poised promoters. An EZH2-T416A mutant (EZH2-mTP5) fails to bind to NIPP1, a factor implied in the regulation of PRC2 binding to a subset of target regions. To obtain a genome wide picture of differential binding of EZH2-WT and the EZH2-mTP5 mutant to promoter regions, the mutant was subjected to DamID/microanalysis as well. DamID of EZH2-WT (2 replicates) and EZH2-mTP5(T416A)(2 replicates) vs. control (Dam without fused protein)(4 samples)
Project description:To gain genome wide information on the association of EZH2 with promoter regions in HeLa cells, DamID experiments and subsequent analysis by promoter arrays (Affymetrix GeneChip Human Promoter 1.0R ) were performed. The DamID method uses fusions of the bacterial Dam DNA methylase and the protein of interest, to direct the enzymatic activity to the protein’s genomic binding sites, where the DNA is methylated. Methylated DNA is then extracted, enriched and further analysed by microarray. EZH2 is the enzymatic subunit of the Polycomb Repressive Complex 2, which deposits the H3K27me3 mark on chromatin. This mark is associated with low gene expression, either in polycomb repressed regions or, in combination with methylation of H3K4, at poised promoters. An EZH2-T416A mutant (EZH2-mTP5) fails to bind to NIPP1, a factor implied in the regulation of PRC2 binding to a subset of target regions. To obtain a genome wide picture of differential binding of EZH2-WT and the EZH2-mTP5 mutant to promoter regions, the mutant was subjected to DamID/microanalysis as well.
Project description:<p>BRCA1 mutations are a hallmark of hereditary ovarian cancer, strongly linked to deficiencies in homologous recombination (HR) DNA repair and impaired DNA replication fork protection. However, its roles in cancer progression beyond maintaining genomic integrity remain poorly understood. Through metabolomics approaches, we found BRCA1-deficiency strikingly increased choline metabolism. Loss of BRCA1 promotes choline uptake through upregulating choline transporter-like protein 4 (CTL4). BRCA1 directly binds and recruits EZH2-mediated H3K27Me3 deposition to CTL4 promoter. CTL4 was therefore overexpressed in ovarian cancer tissues with BRCA1 mutations. Furthermore, BRCA1-deficiency significantly promotes ovarian cancer invasion, while inhibition of CTL4 reverses the high metastatic potential of BRCA1-deficient ovarian cancer cells, suggesting the functionality and specificity of CTL4 as a therapeutic target. Additionally, we discovered that phosphocholine, the choline metabolite increased by CTL4 overexpression, interacted with and stabilized the epithelial-to-mesenchymal transition inducer FAM3C in BRCA1-deficient ovarian cancer cells. Importantly, we identified a potent CTL4 inhibitor, DT-13, which significantly reduces choline metabolism and effectively suppresses metastasis in BRCA1-deficient ovarian cancers. Therefore, our study uncovers a mechanism underlying metastasis in BRCA1-deficient cancers and identifies CTL4 as a therapeutic target for metastatic ovarian cancer patients with BRCA1 mutations.</p>