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In vitro angiogenesis miRNA Array

ABSTRACT: Angiogenesis is a complex multicellular process requiring the orchestration of many events including migration, alignment, proliferation, lumen formation, remodeling, and maturation. Such complexity indicates that not only individual genes but also entire signaling pathways will be crucial in angiogenesis. To define an angiogenic blueprint of regulated genes, we utilized our well-characterized three-dimensional collagen gel model of in vitro angiogenesis, in which the majority of cells synchronously progress through defined morphological stages culminating in the formation of capillary tubes. We developed a comprehensive three-tiered approach using microarray analysis, which allowed us to identify genes known to be involved in angiogenesis and genes hitherto unlinked to angiogenesis as well as novel genes and has proven especially useful for genes where the magnitude of change is small. From a screen of miRNAs altered in in vitro angiogenesis we selected a subset that are predicted to target junctional molecules. MiR-27a, was rapidly downregulated upon stimulation of in vitro angiogenesis and its level of expression is reduced in neo-vessels in vivo. The downregulation of miR-27a was essential for angiogenesis since ectopic expression of miR-27a blocked capillary tube formation and angiogenesis. MiR-27a targets the junctional, endothelial specific cadherin, VE-cadherin. Consistent with this, vascular permeability to VEGF in mice is reduced by administration of a general miR-27 inhibitor. To determine that VE-cadherin was the dominant target of miR-27a function we used a novel technology with “Blockmirs”, inhibitors that bind to the miR-27 binding site in VE-cadherin. The Blockmir CD5-2 demonstrated specificity for VE-cadherin and inhibited vascular leak in vitro and in vivo. Furthermore CD5-2 reduced oedema, increased capillary density and potently enhanced recovery form ischemic limb injury in mice. The Blockmir technology offers a refinement in the use of miRNAs especially for therapy. Further, targeting of endothelial junctional molecules by miRNAs has clinical potential especially in diseases associated with vascular leak.

ORGANISM(S): Homo sapiens

PROVIDER: GSE50437 | GEO | 2013/09/30

SECONDARY ACCESSION(S): PRJNA217489

REPOSITORIES: GEO

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Project description:Angiogenesis is a complex multicellular process requiring the orchestration of many events including migration, alignment, proliferation, lumen formation, remodeling, and maturation. Such complexity indicates that not only individual genes but also entire signaling pathways will be crucial in angiogenesis. To define an angiogenic blueprint of regulated genes, we utilized our well-characterized three-dimensional collagen gel model of in vitro angiogenesis, in which the majority of cells synchronously progress through defined morphological stages culminating in the formation of capillary tubes. We developed a comprehensive three-tiered approach using microarray analysis, which allowed us to identify genes known to be involved in angiogenesis and genes hitherto unlinked to angiogenesis as well as novel genes and has proven especially useful for genes where the magnitude of change is small. From a screen of miRNAs altered in in vitro angiogenesis we selected a subset that are predicted to target junctional molecules. MiR-27a, was rapidly downregulated upon stimulation of in vitro angiogenesis and its level of expression is reduced in neo-vessels in vivo. The downregulation of miR-27a was essential for angiogenesis since ectopic expression of miR-27a blocked capillary tube formation and angiogenesis. MiR-27a targets the junctional, endothelial specific cadherin, VE-cadherin. Consistent with this, vascular permeability to VEGF in mice is reduced by administration of a general miR-27 inhibitor. To determine that VE-cadherin was the dominant target of miR-27a function we used a novel technology with M-bM-^@M-^\BlockmirsM-bM-^@M-^], inhibitors that bind to the miR-27 binding site in VE-cadherin. The Blockmir CD5-2 demonstrated specificity for VE-cadherin and inhibited vascular leak in vitro and in vivo. Furthermore CD5-2 reduced oedema, increased capillary density and potently enhanced recovery form ischemic limb injury in mice. The Blockmir technology offers a refinement in the use of miRNAs especially for therapy. Further, targeting of endothelial junctional molecules by miRNAs has clinical potential especially in diseases associated with vascular leak. A microRNA microarray was performed to investigate miRNAs that were regulated during capillary tube formation and which could potentially be used as an M-bM-^@M-^XangiogenicM-bM-^@M-^Y miRNA profile. RNA was isolated from cells harvested at specific time points, previously identified as stages where major morphological changes are taking place18. These include 0.5 hour (invasion), 3 hours (migration), 6 hours (vacuole coalescence and lumen formation), 12 hours (lumen formation) and 24 hours (tube maturation).

Project description:Rationale: The mechanistic foundation of vascular maturation is still largely unknown. Several human pathologies are characterized by deregulated angiogenesis and unstable blood vessels. Solid tumours, for instance, get their nourishment from newly formed structurally abnormal vessels which present wide and irregular inter-endothelial junctions. Expression and clustering of the main endothelial-specific adherens junction protein, vascular endothelial (VE)-cadherin (VEC), upregulate genes with key roles in endothelial differentiation and stability. Objective: We aim at understanding the molecular mechanisms through which VEC triggers the expression of a set of genes involved in endothelial differentiation and vascular stabilization. Methods and Results: We compared a VEC-null cell line with the same line reconstituted with VEC wild type cDNA. VEC expression and clustering upregulated endothelial-specific genes with key roles in vascular stabilization including claudin-5, Vascular Endothelial-Protein Tyrosine Phosphatase (VE-PTP) and von Willebrand factor (vWf). Mechanistically VEC exerts this effect by inhibiting Polycomb protein activity on the specific gene promoters. This is achieved by preventing nuclear translocation of FoxO1 and β-catenin, which contribute to Polycomb repressive complex-2 (PRC2) binding to promoter regions of claudin-5, VE-PTP and vWf. VE-cadherin/β-catenin complex also sequesters a core subunit of PRC2 (Ezh2) at the cell membrane, preventing its nuclear translocation. Inhibition of Ezh2/VE-cadherin association increases Ezh2 recruitment to claudin-5, VE-PTP and vWf promoters, causing gene downregulation. RNAseq comparison of VEC-null and VEC-positive cells suggested a more general role of VE-cadherin in activating endothelial genes and triggering a vascular stability-related gene expression program. In pathological angiogenesis of human ovarian carcinomas, reduced VEC expression paralleled decreased levels of Claudin-5 and VE-PTP. Conclusions: These data extend the knowledge of Polycomb-mediated regulation of gene expression to endothelial cell differentiation and vessel maturation. The identified mechanism opens novel therapeutic opportunities to modulate endothelial gene expression and induce vascular normalization through pharmacological inhibition of the Polycomb-mediated repression system. Keywords: Polycomb, endothelial cells, VE-cadherin, vessel maturation, vascular biology, vascular permeability, cell signalling, epigenetics, gene regulation. Downloaded from http://circres.ahajour Conclusions: These data extend the knowledge of Polycomb-mediated regulation of gene expression to endothelial cell differentiation and vessel maturation. The identified mechanism opens novel therapeutic opportunities to modulate endothelial gene expression and induce vascular normalization through pharmacological inhibition of the Polycomb-mediated repression system

Project description:Vascular endothelial protein tyrosine phosphatase (VE-PTP, PTPRB) is a receptor type phosphatase that is crucial for the regulation of endothelial junctions and blood vessel development. VE-PTP regulates vascular integrity by dephosphorylating substrates which are key players in endothelial junction stability, such as the angiopoietin receptor TIE2, the endothelial adherens junction protein VE-cadherin and the vascular endothelial growth factor receptor VEGFR2. Here, we have systematically searched for novel substrates of VE-PTP in endothelial cells by utilizing two approaches. First, we studied changes in the endothelial phosphoproteome upon exposing cells to a highly VE-PTP-specific phosphatase inhibitor followed by affinity isolation and mass-spectrometric analysis of phosphorylated proteins by phosphotyrosine-specific antibodies. Second, we used a substrate trapping mutant of VE-PTP to pull down phosphorylated substrates in combination with SILAC-based quantitative mass spectrometry measurements. We identified a set of substrate candidates of VE-PTP, of which a remarkably large fraction is related to cell junctions (48/165; 29.1%). Several of those were found in both screens and displayed very high connectivity in predicted functional interaction networks. The receptor protein tyrosine kinase EPHB4 was the most prominently phosphorylated protein upon VE-PTP inhibition among those VE-PTP targets that were identified by both proteomic approaches. Further analysis revealed that EPHB4 forms a ternary complex with VE-PTP and TIE2 in endothelial cells. VE-PTP controls the phosphorylation of each of these two tyrosine kinase receptors. Despite of their simultaneous presence in a ternary complex, stimulating each of the receptors with their own specific ligand did not cross-activate the respective partner receptor. Our systematic approach has led to the identification of novel substrates of VE-PTP, of which many are relevant for the control of cellular junctions further promoting the importance of VE-PTP as a key player of junctional signalling.

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In vitro angiogenesis miRNA Array

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