Project description:Context dependent molecular cues shape the formation of the cerebral vascular network and the function of the blood-brain barrier (BBB). The Wnt/ß-catenin pathway is orchestrating CNS vascular development, but downstream mediators have not been characterized. Here we generated an endothelial cell-specific R26-Axin1 overexpression (AOE) mouse model to inhibit Wnt/ß-catenin signaling. In AOE mice we discovered that blockade of Wnt/ß-catenin pathway leads to premature regression and remodeling without compromising BBB integrity. Importantly, by comparing transcriptomes of endothelial cells from wildtype and AOE mice, we identified ADAMTSL2 as a novel Wnt/ß-catenin-induced, secreted factor, important for stabilizing the BBB during development. Zebrafish loss-of-function and gain-of-function models, further demonstrated that ADAMTSL2 is crucial for normal vascular development and could rescue vascular phenotypes in AOE zebrafish brains. In conclusion, the studies presented here reveal a hitherto unrecognized role of ADAMTSL2 as an endothelial cell-specific mediator of Wnt/ß-catenin signaling during CNS vascular development and BBB-formation.
Project description:The Wnt/ß-catenin pathway is orchestrating the development of the blood-brain barrier (BBB), but its downstream mediators have remained elusive. To identify potential effectors, we generated an endothelial cell specific Axin1 over-expressing mouse model, AOEiEC. We found that in AOEiE mice Wnt/ß-catenin signalling was down regulated leading to premature regression and remodelling without directly compromising BBB integrity. Interestingly, by comparing transcriptomes of endothelial cells from control and AOEiEC mice, we identified Adamtsl2 as a novel Wnt/ß-catenin-induced, secreted factor, important for stabilizing the cerebral vasculature during development. Importantly, loss-of-function and gain-of-function experiments revealed that Adamtsl2 alone was sufficient to rescue CNS vascular defects seen upon Wnt-signalling inhibition. Furthermore, using various cell and animal models we demonstrate that Adamtsl2 exerts its function by fine-tuning the TGFβ signalling pathway in CNS vessels. In conclusion, this study implicates Adamtsl2 as a mediator of Wnt/ß-catenin signalling during BBB development by linking it to TGFβ signalling.
Project description:Using mice with targeted gene mutations, we identify (1) distinct roles for different canonical Wnt signaling components in central nervous system (CNS) vascular development and in the specification of the blood-brain and blood-retina barriers (BBB and BRB) and (2) differential sensitivities of the vasculature in various CNS regions to perturbations in canonical Wnt signaling components. We find nearly equivalent roles for Lrp5 and Lrp6 in brain vascular development and barrier maintenance but a dominant role for Lrp5 in the retinal vasculature, an especially high sensitivity of the BBB in the cerebellum and pons/interpeduncular nuclei to decrements in canonical Wnt signaling, and plasticity in the barrier properties of mature CNS vasculature. Brain and retinal vascular defects caused by loss of Norrin/Frizzled4 signaling can be fully rescued by stabilizing beta-catenin, and loss of beta-catenin’s transcriptional activation domain or expression of a dominant negative Tcf4 recapitulates the vascular development and barrier defects seen with loss of receptor, co-receptor, or ligand, indicating that Norrin/Frizzled4 signaling acts predominantly by beta-catenin-dependent transcriptional regulation. This work strongly supports a model in which identical or nearly identical canonical Wnt signaling mechanisms mediate neural tube and retinal vascularization and maintain the BBB and BRB. Total retina RNA from P10 WT, NdpKO, Ctnnb1flex3/+;Pdgfb-CreER, and NdpKO;Ctnnb1flex3/+;Pdgfb-CreER mice was subjected to RNAseq
Project description:To address the role of endothelial Wnt/β-catenin signaling in CNS angiogenesis, we compared the bulk transcriptomes of WT and Wnt/β-catenin signaling-deficient PHBC endothelial cells, prior to CNS vascular invasion. To this end, we used three approaches to abrogate endothelial Wnt/β-catenin signaling: Morpholino-mediated knock-down of gpr124, reck or wnt7aa. We find that the expression of mmp25b is decreased in PHBC endothelial cells of all Wnt/β-catenin signaling deficient conditions as compared to the WT controls.
Project description:Genetic and epigenetic defects in Wnt/ß-catenin signaling play important roles in colorectal cancer progression. Here we identify DACT3, a member of the DACT (Dpr/Frodo) gene family, as a negative regulator of Wnt/ß-catenin signaling that is transcriptionally repressed in colorectal cancer. Unlike other Wnt signaling inhibitors that are silenced by DNA methylation, DACT3 repression is associated with bivalent histone modifications. Remarkably, DACT3 expression can be robustly de-repressed by a pharmacological combination that simultaneously targets both histone methylation and deacetylation, leading to strong inhibition of Dishevelled (Dvl)-mediated Wnt/ß-catenin signaling and massive apoptosis of colorectal cancer cells. Our study identifies DACT3 as an important regulator of Wnt/ß-catenin signaling in colorectal cancer and suggests a potential strategy for therapeutic control of Wnt/ß-catenin signaling in colorectal cancer. Keywords: Colon cancer cell line
Project description:Signaling events that regulate central nervous system (CNS) angiogenesis and blood-brain barrier (BBB) formation are only beginning to be elucidated. By evaluating the gene expression profile of mouse vasculature, we identified DR6/TNFRSF21 and TROY/TNFRSF19 as regulators of CNS-specific angiogenesis in both zebrafish and mice. Furthermore, these two death receptors interact both genetically and physically and are required for vascular endothelial growth factor (VEGF)-mediated JNK activation and subsequent human brain endothelial sprouting in vitro. Increasing beta-catenin levels in brain endothelium upregulate DR6 and TROY, indicating that these death receptors are downstream target genes of Wnt/beta-catenin signaling, which has been shown to be required for BBB development. These findings define a role for death receptors DR6 and TROY in CNS-specific vascular development. 5 replicates of 3 time points for either brain or liver/lung facs sorted vascaulture. One adult liver/lung replicate was not used as it failed QC
Project description:Using mice with targeted gene mutations, we identify (1) distinct roles for different canonical Wnt signaling components in central nervous system (CNS) vascular development and in the specification of the blood-brain and blood-retina barriers (BBB and BRB) and (2) differential sensitivities of the vasculature in various CNS regions to perturbations in canonical Wnt signaling components. We find nearly equivalent roles for Lrp5 and Lrp6 in brain vascular development and barrier maintenance but a dominant role for Lrp5 in the retinal vasculature, an especially high sensitivity of the BBB in the cerebellum and pons/interpeduncular nuclei to decrements in canonical Wnt signaling, and plasticity in the barrier properties of mature CNS vasculature. Brain and retinal vascular defects caused by loss of Norrin/Frizzled4 signaling can be fully rescued by stabilizing beta-catenin, and loss of beta-catenin’s transcriptional activation domain or expression of a dominant negative Tcf4 recapitulates the vascular development and barrier defects seen with loss of receptor, co-receptor, or ligand, indicating that Norrin/Frizzled4 signaling acts predominantly by beta-catenin-dependent transcriptional regulation. This work strongly supports a model in which identical or nearly identical canonical Wnt signaling mechanisms mediate neural tube and retinal vascularization and maintain the BBB and BRB.
Project description:24 colon normal and tumor pairs using Illumina BeadChip Human Ref8-v2. Genetic and epigenetic defects in Wnt/ß-catenin signaling play important roles in colorectal cancer progression. Here we identify DACT3, a member of the DACT (Dpr/Frodo) gene family, as a negative regulator of Wnt/ß-catenin signaling that is transcriptionally repressed in colorectal cancer. Unlike other Wnt signaling inhibitors that are silenced by DNA methylation, DACT3 repression is associated with bivalent histone modifications. Remarkably, DACT3 expression can be robustly de-repressed by a pharmacological combination that simultaneously targets both histone methylation and deacetylation, leading to strong inhibition of Dishevelled (Dvl)-mediated Wnt/ß-catenin signaling and massive apoptosis of colorectal cancer cells. Our study identifies DACT3 as an important regulator of Wnt/ß-catenin signaling in colorectal cancer and suggests a potential strategy for therapeutic control of Wnt/ß-catenin signaling in colorectal cancer. The clinical information for the colon tumor is not available. Keywords: human colon tumor
Project description:Signaling events that regulate central nervous system (CNS) angiogenesis and blood-brain barrier (BBB) formation are only beginning to be elucidated. By evaluating the gene expression profile of mouse vasculature, we identified DR6/TNFRSF21 and TROY/TNFRSF19 as regulators of CNS-specific angiogenesis in both zebrafish and mice. Furthermore, these two death receptors interact both genetically and physically and are required for vascular endothelial growth factor (VEGF)-mediated JNK activation and subsequent human brain endothelial sprouting in vitro. Increasing beta-catenin levels in brain endothelium upregulate DR6 and TROY, indicating that these death receptors are downstream target genes of Wnt/beta-catenin signaling, which has been shown to be required for BBB development. These findings define a role for death receptors DR6 and TROY in CNS-specific vascular development.
Project description:Genetic and epigenetic defects in Wnt/?-catenin signaling play important roles in colorectal cancer progression. Here we identify DACT3, a member of the DACT (Dpr/Frodo) gene family, as a negative regulator of Wnt/ß-catenin signaling that is transcriptionally repressed in colorectal cancer. Unlike other Wnt signaling inhibitors that are silenced by DNA methylation, DACT3 repression is associated with bivalent histone modifications. Remarkably, DACT3 expression can be robustly de-repressed by a pharmacological combination that simultaneously targets both histone methylation and deacetylation, leading to strong inhibition of Dishevelled (Dvl)-mediated Wnt/?-catenin signaling and massive apoptosis of colorectal cancer cells. Our study identifies DACT3 as an important regulator of Wnt/ß-catenin signaling in colorectal cancer and suggests a potential strategy for therapeutic control of Wnt/ß-catenin signaling in colorectal cancer. This SuperSeries is composed of the SubSeries listed below.