FGF-dependent regulation of VEGF signaling via transcriptional control of VEGF receptor 2 expression
ABSTRACT: Numerous studies have suggested a link between fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF) signaling pathways; however the nature of this link has not been established. To evaluate this relationship we investigated VEGF signaling in endothelial cells with disrupted FGF signaling in vitro and in vivo. We find that endothelial cells lacking FGF signaling become unresponsive to VEGF due to down regulation of VEGFR2 expression caused by reduced Vegfr2 enhancer activation, which is in turn caused by reduced activation of Ets family transcription factors. In vivo this manifests in the loss of vascular integrity and morphogenesis. Thus, basal FGF stimulation of the endothelium is required for maintenance of VEGFR2 expression and the ability to respond to VEGF stimulation and accounts for the hierarchic control of vascular formation by FGFs and VEGF. Overall design: Primary mouse lung endothelial cells were transduced with either Adeno-Null (empty) or Adeno- dominant negative FGF receptor 1 and harvested 24 hours after transduction. Total RNA was extracted and subjected to the analysis using SuperArray GEArray Q Series Mouse Angiogenesis Gene Array. Comparisons were made between treatments.
Project description:Numerous studies have suggested a link between fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF) signaling pathways; however the nature of this link has not been established. To evaluate this relationship we investigated VEGF signaling in endothelial cells with disrupted FGF signaling in vitro and in vivo. We find that endothelial cells lacking FGF signaling become unresponsive to VEGF due to down regulation of VEGFR2 expression caused by reduced Vegfr2 enhancer activation, which is in turn caused by reduced activation of Ets family transcription factors. In vivo this manifests in the loss of vascular integrity and morphogenesis. Thus, basal FGF stimulation of the endothelium is required for maintenance of VEGFR2 expression and the ability to respond to VEGF stimulation and accounts for the hierarchic control of vascular formation by FGFs and VEGF. Primary mouse lung endothelial cells were transduced with either Adeno-Null (empty) or Adeno- dominant negative FGF receptor 1 and harvested 24 hours after transduction. Total RNA was extracted and subjected to the analysis using SuperArray GEArray Q Series Mouse Angiogenesis Gene Array. Comparisons were made between treatments.
Project description:Rationale: Slit2 is a possible modulator of vascular endothelial growth factor (VEGF) - induced angiogenesis, but its effects have not been tested in large animal models. Objective: We studied the effect of Slit2 on therapeutic angiogenesis induced by VEGF receptor 2 (VEGFR2) ligands Vammin and VEGF-DΔNΔC in vivo in rabbit skeletal muscles. The Slit2 target genes were also studied by RNA sequencing (RNA-Seq) in endothelial cells. Methods and Results: Adenoviral intramuscular gene transfers were performed into rabbit hindlimbs. Confocal and multiphoton microscopy were used for blood vessel imaging. Signaling experiments and gene expression analyses were performed to study mechanisms of Slit2 action. Slit2 decreased VEGFR2-mediated vascular permeability. It also reduced VEGFR2-mediated increase in blood perfusion and capillary enlargement, whereas sprouting of the capillaries was increased. Slit2 gene transfer alone did not have any effects on vascular functions or morphology. VEGFR2 activation was not affected by Slit2, but eNOS phosphorylation was diminished. The transcriptome profiling showed Slit2 downregulating angiogenesis-related genes such as nuclear receptor subfamily 4 group A member 1 (NR4A1) and Stanniocalcin-1 (STC-1) as well as genes related to endothelial cell migration and vascular permeability. Conclusions: Combining Slit2 with VEGFs adjusts VEGFR2-mediated angiogenic effects into a more physiological direction. This possibly allows the use of higher VEGF vector doses to achieve a more widespread vector and VEGF distribution in the target tissues leading to a better therapeutic outcome while reducing excess vascular permeability. HUVEC mRNA profiles after adenoviral vector gene transfers in duplicate.
Project description:MicroRNA expression profiling of human microvascular endothelial cells (HMVECs) treated with either vascular endothelial growth factor (VEGF) only or in combination with the natural angiogenesis inhibitor pigment epithelial-derived factor (PEDF). Originally we were interested in the microRNA-mediated regulation of angiogenesis by the endogenous anti-angiogenic PEDF. To identify the microRNAs involved in PEDF signaling in activated endothelial cells, we compared the levels of microRNAs in non-treated microvascular endothelial cells, cells treated with VEGF, and cells treated with a combination of VEGF and PEDF. After treatment, total RNA content was isolated and sent for analysis to LC Sciences, LLC. They performed expression profiling and completed statistical analysis, based on which we confirmed the regulation of one of the microRNAs, mir-27b. In the following experiments, we identified the targets of mir-27b relevant for angiogenesis and confirmed our findings in zebrafish and mouse models. The manuscript describes the key role of mir-27b in determination of the endothelial tip cell fate and venous differentiation by regulating Notch ligand Delta-like ligand 4 (Dll4) and Sprouty homologue 2 (Spry2). Three-condition experiment: untreated (control) HMVECs vs. VEGF-treated HMVECs vs. PEDF/VEGF-treated HMVECs.
Project description:Angiogenesis is a highly regulated process essential for organ development and maintenance, and its deregulation contributes to inflammation, cardiac disorders and cancer. The Ca2+/Nuclear Factor of Activated T-cells (NFAT) signaling pathway is central to endothelial cell angiogenic responses, and it is activated by stimuli like the vascular endothelial growth factor A (VEGF). NFAT phosphorylation by dual-specificity tyrosine phosphorylation-regulated kinases (DYRKs) is thought to be an inactivating event. Contrary to expectations, we show that the DYRK family member DYRK1A positively regulates VEGF-dependent NFAT transcriptional responses in primary endothelial cells. DYRK1A silencing reduces intracellular Ca2+ influx in response to VEGF, which dampens NFAT activation. The effect is exerted at the level of VEGFR2 accumulation leading to impairment in PLCg1 activation. Notably, Dyrk1a heterozygous mice show defects in developmental retinal vascularization. Our data establish a regulatory circuit, DYRK1A/ Ca2+/NFAT, to fine-tune endothelial cell proliferation and angiogenesis. Overall design: RNA microarray analysis using VEGF-stimulated HUVECs infected with lentivirus expressing a control shRNA or a shRNA targeting DYRK1A. To discriminate the NFAT-dependent group of genes, VEGF-stimulated cells in the presence of the CN/NFAT inhibitor cyclosporin A (CsA) were analyzed.
Project description:Lymphatic vessel growth and activation, mediated by vascular endothelial growth factor- (VEGF)-C and/or VEGF-A, play an important role in metastatic cancer spread and in chronic inflammation. We aimed to comprehensively identify downstream molecular targets induced by VEGF-A or VEGF-C in lymphatic endothelium. To this end, we treated human dermal lymphatic endothelial cells (LEC) with VEGF-A or VEGF-C for up to 24 hours, followed by a time-series transcriptional profiling using gene microarray technology. We identified a number of genes - many of them not previously known to be involved in lymphangiogenesis - that clustered either as early response genes, transiently induced genes or progressively induced genes. Endothelial specific molecule-1 (ESM-1) was one of the genes that were most potently induced by both VEGF-A and VEGF-C. Keywords: Time course, growth factor comparison Overall design: Overnight serum starved human primary dermal microvascular lymphatic endothelial cells (LEC; passage 5-7) were stimulated with either VEGF-A or VEGF-C for 24 hours, 8 hours, 4 hours and 1 hour. Total RNA from all samples were isolated using TriZol at time point zero (control reference point). Treatments were performed at three independent times (triplicates) for each growth factor and at each time point (except the control reference time point), total of 27 samples and labeled and hybridized using the AB1700 microarray platform.
Project description:To profile changes in gene expression in human endothelial cells in response to VEGF-A165 and phenotypic changes during vascular network formation in vitro 16 samples of human umbilical vein endothelial cells were analysized, four distinct biological samples were used in each condition. The four conditions included: VEGF treatment in Matrigel culture, Mock treatment in Matrigel culture, VEGF treatment in 2D monolayer, and mock treatment in 2D monolayer.
Project description:Vascular endothelial growth factor A (VEGF-A) is a master regulator of vascular development and function. Consequently, VEGF-A regulated gene expression programs have been under heavy research. In this study we study the transcriptional regulation of VEGF-A-responsive genes in primary aortic endothelial cells (HAEC) and vein endothelial cells (HUVEC) using genome wide global run-on sequencing (GRO-Seq). We show that half of VEGF-A induced genes display a paused phenotype under basal conditions and are thus poised for rapid gene activation. Promoters of paused genes are distinguished from those of non-paused by higher basal enrichment for active histone marks H3K4me3, H3K9ac and H3K27ac. We also show that nearly 100% of the VEGF-upregulated genes are induced at the level of elongation, whereas 38-53% are also induced at the level of initiation. We also report a comprehensive chromatin interaction map generated in HUVECs using tethered conformation capture (TCC) and characterize chromatin interactions in relation to transcriptional activity. We demonstrate that sites of active transcription are more likely to engage in chromatin looping and identify chromatin compartments enriched for VEGF-regulated genes. Cell-type specific transcriptional activity was also shown to reflect boundaries of chromatin interactions within the HOXA cluster. Collectively, these findings provide new insight into mechanisms behind VEGF-A-regulated transcriptional programs in endothelial cells. ChIP-Seq (H3K4me2), GRO-Seq and HiC profiling was performed in HUVECs and HAECs.
Project description:Human umbilical vein vascular endothelial cells (HUVECs) are crucial for angiogenesis that benefits functional recovery after cerebral infarction. This study aims to investigate the mechanisms underlying the effects of vascular endothelial growth factor (VEGF) on HUVECs. HUVECs were treated with 16 ng/mL VEGF165 for 4 days
Project description:Angiogenic homeostasis is maintained by a balance between vascular endothelial growth factor (VEGF) and Notch signalling in endothelial cells (ECs). We screened for molecules that might mediate the coupling of VEGF signal transduction with down-regulation of Notch signalling, and identified B-cell chronic lymphocytic leukemia/lymphoma6-associated zinc finger protein (BAZF). BAZF was induced by VEGF-A in ECs to bind to the Notch signalling factor CBF1, and to promote the degradation of CBF1 through polyubiquitination in a CBF1-cullin3 (CUL3) E3 ligase complex. BAZF disruption in vivo decreased endothelial tip cell number and filopodia protrusion, and markedly abrogated vascular plexus formation in the mouse retina, overlapping the retinal phenotype seen in response to Notch activation. Further, impaired angiogenesis and capillary remodeling were observed in skin-wounded BAZF-/- mice. We therefore propose that BAZF supports angiogenic sprouting via BAZF-CUL3-based polyubiquitination-dependent degradation of CBF1 to down-regulate Notch signalling. Overall design: Human umbilical vein endothelial cells were stimulated with recombinant human VEGF165 for 0, 1, 2, 6, 12, 24 and 48 hours.