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Wnt/β-catenin signaling regulates VE-cadherin-mediated anastomosis of brain capillaries by counteracting S1pr1 signaling

ABSTRACT: Canonical Wnt signaling is crucial for vascularization of the central nervous system and blood-brain barrier (BBB) formation. BBB formation and modulation are not only important for development, but also relevant for vascular and neurodegenerative diseases. However, beyond the early requirement of Wnt signaling for brain capillary development, there is little understanding of how Wnt signaling further contributes to brain angiogenesis and BBB formation. By combining high resolution in vivo imaging with temporally and spatially controlled manipulation of Wnt signaling, we were able to dissect different requirements for Wnt signaling during brain angiogenesis and BBB formation. In the absence of Wnt signaling, premature Sphingosine-1-phosphate receptor (S1pr) signaling leads to a reduction of VE-cadherin and Esama at cell-cell junctions. Wnt signaling most likely suppresses S1pr signaling during angiogenesis to enable the dynamic junction formation during anastomosis, whereas later S1pr signaling regulates BBB maturation and VE-cadherin stabilization. Our data provides a novel link between brain capillary angiogenesis and BBB formation and identifies Wnt signaling as coordinator of the timing and as regulator of anastomosis.

ORGANISM(S): Danio rerio

PROVIDER: GSE121041 | GEO | 2018/10/12

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: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.

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Wnt/β-catenin signaling regulates VE-cadherin-mediated anastomosis of brain capillaries by counteracting S1pr1 signaling

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