Project description:Apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like 3 (APOBEC3B, A3B) is a key molecular driver inducing mutations in multiple human cancer. A3B belongs to the APOBEC3 enzyme family, which consists seven closely related DNA deaminases that catalyse cytosine-to-uracil (C>U) editing of single-stranded DNA (ssDNA). By using mass-spec proteomics, we identified TDRD3, a ‘reader’ of asymmetrically methylated arginine marks, as the binding partner of A3B.
Project description:Specific sites of histone tail methylation are associated with transcriptional activity at gene loci. These methyl-marks are interpreted by effector molecules, which harbor protein domains that bind the methylated motifs and facilitate either active or inactive states of transcription. CARM1 and PRMT1 are transcriptional coactivators that deposit H3R17me2a and H4R3me2a marks, respectively. We used a protein domain microarray approach to identify the tudor domain-containing protein TDRD3 as a “reader” of these marks. Importantly, TDRD3 itself is a transcriptional coactivator. This coactivator activity requires an intact tudor domain. TDRD3 is recruited to an estrogen responsive element in a CARM1-dependent manner. Furthermore, ChIP-seq analysis of TDRD3 reveals that it is predominantly localized to transcriptional start site. Thus, TDRD3 is an effector molecule that promotes transcription by binding methylarginine marks on histone tails. ChIP seq analysis of TDRD3 in MCF7 cells
Project description:Specific sites of histone tail methylation are associated with transcriptional activity at gene loci. These methyl-marks are interpreted by effector molecules, which harbor protein domains that bind the methylated motifs and facilitate either active or inactive states of transcription. CARM1 and PRMT1 are transcriptional coactivators that deposit H3R17me2a and H4R3me2a marks, respectively. We used a protein domain microarray approach to identify the tudor domain-containing protein TDRD3 as a “reader” of these marks. Importantly, TDRD3 itself is a transcriptional coactivator. This coactivator activity requires an intact tudor domain. TDRD3 is recruited to an estrogen responsive element in a CARM1-dependent manner. Furthermore, ChIP-seq analysis of TDRD3 reveals that it is predominantly localized to transcriptional start site. Thus, TDRD3 is an effector molecule that promotes transcription by binding methylarginine marks on histone tails.
Project description:While protein arginine methyltransferases (PRMTs) and PRMT-catalyzed protein methylation have been well-known to be involved in a myriad of biological processes, their roles in carcinogenesis, particularly in estrogen receptor alpha (ERa)-positive breast cancers, remain incompletely understood. Here we focused on investigating PRMT4 (also called coactivator associated arginine methyltransferase 1, CARM1) due to its high expression and the associated poor prognosis in ERa-positive breast cancers. We first uncovered the chromatin-binding landscape and transcriptional targets of CARM1 in the presence of estrogen in ERa-positive breast cancer cells employing genomic and transcriptomics approaches. CARM1 was found to be predominantly and specifically recruited to ERa-bound active enhancers and essential for the transcriptional activation of cognate estrogen-induced gene transcriptional activation in response to estrogen. Global mapping of CARM1 substrates revealed that CARM1 methylates a large cohort of proteins with diverse biological functions, including regulation of intracellular estrogen receptor signaling, chromatin organization, chromatin remodeling and others. Intriguingly, a number of proteins were hypermethylated exclusively by CARM1 on a cluster of arginine residues. Exemplified by MED12, hypermethylation of these proteins by CARM1 served as a molecular beacon for recruiting coactivator protein, tudor domain-containing 3 (TDRD3), to ensure the full activation of estrogen/ERa target genes. In consistent with its critical role in estrogen-induced gene transcriptional activation, CARM1 was found to promote cell proliferation of ERa-positive breast cancer cells in vitro and tumor growth in mice. Taken together, our study uncovered a “hypermethylation” strategy utilized by CARM1 in gene transcriptional regulation, and suggested that CARM1 can server as a therapeutic target for breast cancer treatment.
Project description:To investigate the impact of histone variants and modification on gene regulation, we report high-throughput profiles of six histone markers, H2A.Z, H3K4me2, H3K9me3, H3K27me3, H3K27ac, and H3K36me3, by ChIP-Seq in T-47D breast cancer cells. Libraries were sequenced with the Illumina HiSeq 2000 analyzer for 50 bp paired-end reads and over 20 million uniquely aligned reads were collected for each histone marker. To examine the impact of histone modification on gene expression regulation in T-47D cells.
Project description:R-loops, which consist of a DNA/RNA hybrid and a displaced single-stranded DNA (ssDNA), are increasingly recognized as critical regulators of chromatin biology. R-loops are particularly enriched at gene promoters, where they play important roles in regulating gene expression. However, the molecular mechanisms that control promoter-associated R-loops remain unclear. The epigenetic “reader” Tudor domain-containing protein 3 (TDRD3), which recognizes methylarginine marks on histones and on the C-terminal domain of RNA polymerase II, was previously shown to recruit DNA topoisomerase 3B (TOP3B) to relax negatively supercoiled DNA and prevent R-loop formation. Here, we further characterize the function of TDRD3 in R-loop metabolism and introduce the DExH-box helicase 9 (DHX9) as a novel interaction partner of the TDRD3/TOP3B complex. TDRD3 directly interacts with DHX9 via its Tudor domain. This interaction is important for recruiting DHX9 to target gene promoters, where it resolves R-loops in a helicase activity-dependent manner to facilitate gene expression. Additionally, TDRD3 also stimulates the helicase activity of DHX9. This stimulation relies on the OB-fold of TDRD3, which likely binds the ssDNA in the R-loop structure. Thus, DHX9 functions together with TOP3B to suppress promoter-associated R-loops. Collectively, these findings reveal new functions of TDRD3 and provide important mechanistic insights into the regulation of R-loop metabolism.
Project description:While protein arginine methyltransferases (PRMTs) and PRMT-catalyzed protein methylation have been well-known to be involved in a myriad of biological processes, their roles in carcinogenesis, particularly in estrogen receptor alpha (ERa)-positive breast cancers, remain incompletely understood. Here we focused on investigating PRMT4 (also called coactivator associated arginine methyltransferase 1, CARM1) due to its high expression and the associated poor prognosis in ERa-positive breast cancers. We first uncovered the chromatin-binding landscape and transcriptional targets of CARM1 in the presence of estrogen in ERa-positive breast cancer cells employing genomic and transcriptomics approaches. CARM1 was found to be predominantly and specifically recruited to ERa-bound active enhancers and essential for the transcriptional activation of cognate estrogen-induced gene transcriptional activation in response to estrogen. Global mapping of CARM1 substrates revealed that CARM1 methylates a large cohort of proteins with diverse biological functions, including regulation of intracellular estrogen receptor signaling, chromatin organization, chromatin remodeling and others. Intriguingly, a number of proteins were hypermethylated exclusively by CARM1 on a cluster of arginine residues. Exemplified by MED12, hypermethylation of these proteins by CARM1 served as a molecular beacon for recruiting coactivator protein, tudor domain-containing 3 (TDRD3), to ensure the full activation of estrogen/ERa target genes. In consistent with its critical role in estrogen-induced gene transcriptional activation, CARM1 was found to promote cell proliferation of ERa-positive breast cancer cells in vitro and tumor growth in mice. Taken together, our study uncovered a “hypermethylation” strategy utilized by CARM1 in gene transcriptional regulation, and suggested that CARM1 can server as a therapeutic target for breast cancer treatment.
Project description:The goal of the project was global identification of CARM1 substrates. Arginine methylation landscapes were profiled and compared in wild type and CARM1 knockout cells to determine in vivo substrates of CARM1.
Project description:CARM1 is an arginine methyltransferase that asymmetrically dimethylates protein substrates on arginine residues. CARM1 is often overexpressed in cancers and stimulates growth. However, clinically applicable therapeutic strategies based on CARM1 expression in cancer remains to be explored. Here we show that epithelial ovarian cancer is among the cancers with the highest CARM1 amplification rates that predicates a shorter survival. Our unbiased screen show that CARM1-expressing ovarian cancer cells are selectively sensitive to the inhibition of EZH2, another epigenetic regulator that silences its target genes. Inhibition of EZH2 activity using a clinically applicable small molecule inhibitor significantly suppressed the growth of CARM1-expressing ovarian tumors in two xenograft models. The observed selectivity correlates with upregulation of EZH2 target genes in a CARM1-dependent manner. CARM1 promotes EZH2 dependent gene silencing by methylating BAF155 to alter the antagonism between EZH2 and BAF155. Together, these results indicate that pharmacological inhibition of EZH2 is a novel therapeutic strategy for CARM1-expressing cancers.
Project description:The goal of this study is to identify ERalpha-target genes affected by overexpression of the histone arginine methyltransferase CARM1 in breast cancer cells. The roles of CARM1 in ERalpha+ breast cancer was not well characterized. Therefore, we created a Dox inducible CARM1 overexpressing MCF7 cell line where CARM1 is overexpressed by 2 fold to determine the created a Dox-inducible CARM1 overexpressing MCF7 cells for evaluation of the global effects of CARM1 on Eralpha-target gene expression. MCF7-tet-on-CARM1 clone 13 were treated under 4 conditions: DMSO; Dox; E2 (10nM); Dox+E2. In Dox+E2 condition, cells were pre-treated with Dox for 5 days before treating with E2 for 4 hours. 3 biological replicates were included and total of 12 samples were analyzed.