Project description:RNA polymerase II (RNAPII) pausing release is a recently recognized checkpoint for transcriptional regulation. The biological roles of RNAPII pausing release and the mechanisms that by which extracellular signals control it are incompletely understood. Here we identify a novel mechanism by which VEGF stimulates RNAPII pausing-release through acetylation of ETS1, a master endothelial cell transcriptional regulator. In endothelial cells (ECs), ETS1 uniquely bound transcribed gene promoters and stimulated their expression by broadly increasing RNA polymerase II (RNAPII) pause release. VEGF enhanced ETS1 chromatin occupancy. Furthermore, VEGF increased ETS1 acetylation, enhancing its binding by BRD4 and thereby stimulating RNAPII pause release. This ETS1-mediated transduction of VEGF signaling to increase RNAPII pausing release was essential for EC angiogenic responses in vitro and in vivo. Together, our results define a new angiogenic pathway in which VEGF enhances ETS1-Brd4 interaction to broadly promote RNAPII pause release and drive angiogenesis.
Project description:The bivalent domain at promoter region is a unique epigenetic feature poised for activation or repression during cell differentiation in embryonic stem cell. However, the function of bivalent domains in already differentiated cells remains exclusive. By profiling the epigenetic landscape of endothelial cells during VEGFA stimulation, we discovered that bivalent domains are widespread in endothelial cells and preferentially marked genes responsive to VEGFA. The bivalent domains responsive to VEGFA have more permissive chromatin environment comparing to other bivalent domains. The initial activation of bivalent genes depends on RNAPII pausing release induced by EZH1 rather than removal of H3K27me3. The later suppression of bivalent gene expression depended on KDM5A recruitment by its interaction with PRC2. Importantly, EZH1 promoted both in vitro and in vivo angiogenesis by upregulating EGR3, whereas KDM5A dampened angiogenesis. Collectively, this study demonstrated a novel dual function of bivalent domains in endothelial cells to control VEGF responsiveness and angiogenesis.
Project description:RNAPII pausing/termination shortly after initiation is a hallmark of gene regulation. However, the molecular mechanisms involved are still to be uncovered. Here, we show that NELF interacts with Integrator complex subunits (INTScom) forming a stable complex with RNPII and Spt5. The interaction between NELF and INTScom subunits is RNA and DNA independent. Using both HIV-1 promoter and genome wide analyses, we demonstrate that Integrator subunits specifically control NELF-mediated RNAPII pause/release at coding genes. The strength of RNAPII pausing is determined by the nature of the NELF-associated complex. Interestingly, in addition to controlling RNAPII pause release INTS11 catalytic subunit of the INTScom is required for the synthesis of full length mRNA. Finally, INTScom-target genes are enriched in HIV-1 TAR/ NELF-binding element and in a 3’box sequence required for snRNA biogenesis. Revealing these unexpected functions of INTScom in regulating RNAPII pausing/release and completion of mRNA synthesis of NELF-target genes will contribute to our understanding of the gene expression cycle. Genome-wide expression in HeLa cells in the absence of Integrator 11, or NELF or mock (control) depleted by strand-specific RNASeq (Illumina)
Project description:RNAPII pausing/termination shortly after initiation is a hallmark of gene regulation. However, the molecular mechanisms involved are still to be uncovered. Here, we show that NELF interacts with Integrator complex subunits (INTScom) forming a stable complex with RNPII and Spt5. The interaction between NELF and INTScom subunits is RNA and DNA independent. Using both HIV-1 promoter and genome wide analyses, we demonstrate that Integrator subunits specifically control NELF-mediated RNAPII pause/release at coding genes. The strength of RNAPII pausing is determined by the nature of the NELF-associated complex. Interestingly, in addition to controlling RNAPII pause release INTS11 catalytic subunit of the INTScom is required for the synthesis of full length mRNA. Finally, INTScom-target genes are enriched in HIV-1 TAR/ NELF-binding element and in a 3’box sequence required for snRNA biogenesis. Revealing these unexpected functions of INTScom in regulating RNAPII pausing/release and completion of mRNA synthesis of NELF-target genes will contribute to our understanding of the gene expression cycle. Binding profiles of Integrator subunits in HeLa cells by ChIP-Seq (Illumina) Please note that the MACS14*.tar.gz contains MACS output bed and xls files and the 'readme.txt' contains a detailed description of each file.
Project description:Lysine-specific demethylase 1 (LSD1) catalyzes the demethylation at H3K4 and H3K9 and is well- known for its role in decommissioning enhancers during mouse embryonic stem cell (ESC) differentiation. However, its role at gene promoters remains poorly understood in ESCs despite their widespread presence at these sites. Here, we report that LSD1 promotes RNA Polymerase II (RNAPII) pausing, a rate-limiting step in transcription regulation, in ESCs. We found that the knockdown of LSD1 preferentially affects genes with higher RNAPII pausing than those with lower pausing. We show that LSD1 knockdown leads to the global reduction in RNAPII pausing and most significantly on the genes bound by LSD1. Next, we demonstrate that the co-localization of LSD1 and MYC, a factor known to regulate pause-release, is associated with the enrichment of other RNAPII pausing factors. Finally, we found that genes co-occupied by LSD1 and MYC are significantly enriched for housekeeping genes that are involved in metabolic processes and depleted of transcription factors compared to those bound only by LSD1. Our integrative analysis reveals a pleiotropic role of LSD1 in promoting RNAPII pausing and in regulating housekeeping programs besides its known role in regulating cell identity programs.
Project description:Gene expression by RNA Polymerase II (RNAPII) is tightly controlled by Cyclindependent kinases (CDKs) at discrete checkpoints during the transcription cycle. The RNAPII pausing checkpoint, engaged after transcription initiation, is controlled by CDK9 to regulate transcription in metazoans. We discovered that CDK9-mediated RNAPII pause-release is functionally opposed by a protein phosphatase 2A (PP2A) complex. PP2A dynamically competes for key CDK9 substrates, DSIF and RNAPIICTD, and is recruited to transcription pausing sites by the Integrator complex subunit INTS6. INTS6 depletion confers resistance to CDK9 inhibition in a variety of normal and tumor cell lines. Loss of INTS6 abolishes the Integrator-PP2A association leading to unrestrained CDK9 activity, which amplifies transcriptional responses. Pharmacological PP2A activation synergizes with CDK9 inhibition to kill MLLrearranged leukemias and solid tumors and provide therapeutic benefit in vivo. These data demonstrate that finely-tuned gene expression relies on the balance of kinase and phosphatase activity at the pausing checkpoint.
Project description:RNAPII pausing/termination shortly after initiation is a hallmark of gene regulation. However, the molecular mechanisms involved are still to be uncovered. Here, we show that NELF interacts with Integrator complex subunits (INTScom) forming a stable complex with RNPII and Spt5. The interaction between NELF and INTScom subunits is RNA and DNA independent. Using both HIV-1 promoter and genome wide analyses, we demonstrate that Integrator subunits specifically control NELF-mediated RNAPII pause/release at coding genes. The strength of RNAPII pausing is determined by the nature of the NELF-associated complex. Interestingly, in addition to controlling RNAPII pause release INTS11 catalytic subunit of the INTScom is required for the synthesis of full length mRNA. Finally, INTScom-target genes are enriched in HIV-1 TAR/ NELF-binding element and in a 3’box sequence required for snRNA biogenesis. Revealing these unexpected functions of INTScom in regulating RNAPII pausing/release and completion of mRNA synthesis of NELF-target genes will contribute to our understanding of the gene expression cycle.
Project description:RNAPII pausing/termination shortly after initiation is a hallmark of gene regulation. However, the molecular mechanisms involved are still to be uncovered. Here, we show that NELF interacts with Integrator complex subunits (INTScom) forming a stable complex with RNPII and Spt5. The interaction between NELF and INTScom subunits is RNA and DNA independent. Using both HIV-1 promoter and genome wide analyses, we demonstrate that Integrator subunits specifically control NELF-mediated RNAPII pause/release at coding genes. The strength of RNAPII pausing is determined by the nature of the NELF-associated complex. Interestingly, in addition to controlling RNAPII pause release INTS11 catalytic subunit of the INTScom is required for the synthesis of full length mRNA. Finally, INTScom-target genes are enriched in HIV-1 TAR/ NELF-binding element and in a 3’box sequence required for snRNA biogenesis. Revealing these unexpected functions of INTScom in regulating RNAPII pausing/release and completion of mRNA synthesis of NELF-target genes will contribute to our understanding of the gene expression cycle.
Project description:Dr. Panjwani's laboratory is focusing on the mechanism by which galectins-3 and 7 mediate corneal epithelial cell migration. Recently published studies, that we have confirmed and expended on in our laboratory, clearly demonstrate that galectin-3 mediates angiogenesis in vitro and in vivo. More interestingly we have found that bFGF- and VEGF-mediated angiogenesis can be inhibited by galectin-3 inhibitors, which suggests an important role of carbohydrate recognition systems in the process of angiogenesis. In an effort to characterize the role of carbohydrate recognition system in angiogenesis, we are interested to evaluate and compare the glyco-gene expression profile of endothelial cells stimulated with VEGF, bFGF and galectin-3 at time and concentration at which, the compounds stimulate angiogenesis in vitro. RNA preparations of Galectin-3, VEGF, bFGF, Media Control biological replicates were sent to Microarray Core (E). The RNA was amplified, labeled, and hybridized to GLYCO_v3 microarrays.
Project description:PDGF-C mediates the angiogenic and tumorigenic properties of fibroblasts associated with tumors refractory to anti-VEGF treatment Tumor associated fibroblasts (TAF) from different tumors exhibit distinct angiogenic and tumorigenic properties. Unlike normal skin fibroblasts (NSF) or TAF (TAF-TIB6) from TIB6 tumors that are sensitive to anti-VEGF treatment, TAF (TAF-EL4) from resistant EL4 tumors can stimulate TIB6 tumor growth even when VEGF is inhibited. We show that platelet-derived growth factor (PDGF)-C is upregulated in TAFs from resistant tumors. PDGF-C neutralizing antibodies blocked the angiogenesis induced by such TAF in vivo and slowed the growth of EL4 and admixture (TAF-EL4 + TIB6) tumors and exhibited additive effects with anti-VEGF-A antibodies. Hence, our data reveal a novel mechanism for TAF mediated tumorigenesis and suggest that some tumors may overcome inhibition of VEGF-mediated angiogenesis through upregulation of PDGF-C