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:SPRY4-IT1 (SPRY4 intronic transcript 1) is a long non-coding RNA (lncRNA) that was identified as a novel oncogene in various human cancers, including glioma. However, its function and the further mechanism in glioma remain largely unclear. Here, we aimed to investigate the role of SPRY4-IT1 in the development of glioma and its underlying molecular mechanism. We identify that SPRY4-IT1 is overexpressed in patients with glioma from the TCGA database and own cohort, and correlated with poor prognosis of patients. Then, loss of function and gain of function cell model were established by transfected with siRNA and pcDNA3.1 plasmid. SPRY4-IT1 promotes glioma cells proliferation by Cell Count Kit 8 assays and EdU assay in vitro, and xenograft tumor assays in vivo. RNA sequence was performed to compare the transcriptomes of U87 siSPRY4-IT1-NC and U87 siSPRY4-IT1 cells, and Gene Ontology (GO) enrichment analysis indicated angiogenesis is significantly enriched. HUVEC tube forming assays and Chick Embryo Chorioallantoic Membrane (CAM) assays confirmed that SPRY4-IT1 can induce angiogenesis of glioma in vitro and in vivo. Mechanistically, we identify that SPRY4-IT1 upregulates EZH2 expression by sponge miR-101-3p to induce VEGFA expression in glioma cells. Moreover, SPRY4-IT1 activates VEGFR2/AKT/ERK1/2 pathway in HUVECs by glioma cell-mediated. Rescue experiments were performed by co-transfected with SPRY4-IT1 and EZH2 overexpression plasmid in glioma cells, and confirmed that SPRY4-IT1 promotes cell proliferation and angiogenesis of glioma by miR-101-3p/EZH2/VEGFA signaling axis. Taken together, our studies clarify that SPRY4-IT1 upregulates EZH2 to induce VEGFA by sponge miR-101-3p to achieve cell proliferation and angiogenesis in glioma. Thus, these findings have provided insights into the prognosis prediction and therapeutic target of glioma.
Project description:VEGFA signaling is crucial for physiological and pathological angiogenesis and hematopoiesis. Although many context-dependent signaling pathways downstream of VegfA have been uncovered, vegfa transcriptional regulation in vivo is unclear. Here, we show that ETS transcription factor Etv6 positively regulates vegfa expression during blood stem cell development through multiple transcriptional inputs. In agreement with its established repressive functions, Etv6 directly inhibits expression of vegfa repressor foxo3. Surprisingly, it also directly activates expression of vegfa activator klf4. Finally, it indirectly binds to vegfa promoter by the recruiment of Klf4. Thus, our work uncovers a dual function for Etv6, as both a transcriptional repressor and activator, in controlling a major signaling pathway.
Project description:VEGFA signaling is crucial for physiological and pathological angiogenesis and hematopoiesis. Although many context-dependent signaling pathways downstream of VegfA have been uncovered, vegfa transcriptional regulation in vivo is unclear. Here, we show that ETS transcription factor Etv6 positively regulates vegfa expression during blood stem cell development through multiple transcriptional inputs. In agreement with its established repressive functions, Etv6 directly inhibits expression of vegfa repressor foxo3. Surprisingly, it also directly activates expression of vegfa activator klf4. Finally, it indirectly binds to vegfa promoter by the recruiment of Klf4. Thus, our work uncovers a dual function for Etv6, as both a transcriptional repressor and activator, in controlling a major signaling pathway.
Project description:Here we report that Nono instead functions as a chromatin regulator cooperating with Erk to regulate mESC pluripotency. We demonstrate that Nono loss leads to robust self-renewing mESCs with enhanced expression of Nanog and Klf4, epigenome and transcriptome re-patterning to a “ground-like state” with global reduction of H3K27me3 and DNA methylation resembling the Erk inhibitor PD03 treated mESCs and 2i (both GSK and Erk kinase inhibitors)-induced “ground state”. Mechanistically, Nono and Erk co-bind at a subset of development-related, bivalent genes. Ablation of Nono compromises Erk activation and RNA polymerase II C-terminal Domain serine 5 phosphorylation, and while inactivation of Erk evicts Nono from chromatin, revealing reciprocal regulation. Furthermore, Nono loss results in a compromised activation of its target bivalent genes upon differentiation and the differentiation itself. These findings reveal an unanticipated role of Nono in collaborating with Erk signaling to regulate the integrity of bivalent domain and mESC pluripotency.
Project description:Inflammation is a key component of pathological angiogenesis. Here we monitor gene expression profiles of the pre-sprouting phase of corneal angiogenesis in the rat model, as influenced by topically applied treatments. We used GeneChip Rat Genome 230 2.0 Array to monitor gene expression profies of several genes in the different treatment groups
Project description:Trimethylation of histone 3 lysine 4 (H3K4me3) at promoters of actively transcribed genes is a universal epigenetic mark and a key product of Trithorax-Group action. Here we show that Mll2, one of the six Set1/Trithorax-type H3K4 methyltransferases in mammals, is required for trimethylation of bivalent promoters in mouse embryonic stem cells. Mll2 is bound to bivalent promoters but also to most active promoters, which do not require Mll2 for H3K4me3 or mRNA expression. In contrast, the Set1 complex (Set1C) subunit Cxxc1 is primarily bound to active but not bivalent promoters. This indicates that bivalent promoters rely on Mll2 for H3K4me3 whereas active promoters have more than one bound H3K4 methyltransferase including Set1C. Removal of Mll1, sister to Mll2, had almost no effect on any promoter unless Mll2 was also removed indicating functional back-up between these enzymes. Except for a subset, loss of H3K4me3 on bivalent promoters did not prevent responsiveness to retinoic acid thereby arguing against a priming model for bivalency. In contrast, we propose that Mll2 is the pioneer trimethyltransferase for promoter definition in the naM-CM-/ve epigenome and Polycomb-Group action on bivalent promoters blocks premature establishment of active, Set1C bound, promoters. ChIP-Seq to study MLL2 function using H3K4me3 (12 samples), H3K27me3 (4 samples), Pol2 (1 sample) or GFP (7 samples) antibody, and 6 RNA-Seq profiles
Project description:The GPR124/RECK/WNT7 pathway essentially regulates central nervous system angiogenesis and blood-brain barrier (BBB) function. GPR124, a brain endothelial adhesion 7-pass transmembrane protein, associates with membrane RECK, which binds and stabilizes newly synthesized WNT7 for subsequent transfer to Frizzled (FZD) and canonical b-catenin signaling. GPR124 function remains enigmatic; while its extracellular domain (ECD) is required, the poorly conserved intracellular domain (ICD) appears to be variably required in mammals versus zebrafish, potentially mediated by bridging of the GPR124 and FZD ICDs by intracellular adaptor proteins. GPR124 ICD deletion mutants impair zebrafish angiogenesis, but paradoxically still mediate WNT7 signaling upon mammalian cell transfection. We thus further investigated the GPR124 C-terminal ICD by deletion in mice (Gpr124ΔC). Notably, Gpr124ΔC/ΔC mice could be born and did not recapitulate Gpr124-/- embryonic lethal forebrain hemorrhage. GPR124ΔC protein was inefficiently expressed, resulting in mild, hypomorphic, non-hemorrhagic defects in CNS angiogenesis and BBB function, sparing the cortex and only confined to ganglionic eminences. Impaired surface expression of GPR124ΔC directly correlated with reduced endothelial WNT signaling, arguing against an intrinsic signaling deficiency. Further, GPR124ΔC and recombinant GPR124 ECD both rescued WNT7 signaling following brain endothelial Gpr124 knockdown. Thus, in mice, the GPR124 essential regulation of WNT7-dependent CNS forebrain angiogenesis and BBB function is exerted by ICD-independent functionality, extending the range of signaling mechanisms used by adhesion 7-pass transmembrane receptors.
Project description:Purpose: We report expression of a new Cas13 enzyme in retinal cells and evaluate its efficacy in targeting the VEGFA mRNA to establish safety and efficacy of the enzyme got anti-VEGFA therapy. Methods: Three retinal organoids were cultured and treated, (1) Untreated, (2) AAV2.7m8.Cas13bt3.VEGFA.sgRNA, (3) AAV2.7m8.Cas13bt3.NTsgRNA. Single-cell RNA sequencing was performed to determine expression of Cas13bt3 across retinal cell types, and the corresponding VEGFA mRNA expression. Results: All retinal cell showed observable transduction and RPE cells were found most susceptible to infection, while bipolar cells had the least infection rate. Significant silencing of VEGFA was observed in RPE cells. Conclusions: AAV2.7m8 can be used for retina-wide transduction, and Cas13bt3 may be a potential new tool for control of VEGFA.