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.

Project description:The study of epigenetic mechanisms of gene regulation and the role of these mechanisms in developmental reprogramming of the genome and disease susceptibility has increased in recent years. Molecular epigenetic mechanisms regulating gene expression include DNA methylation, histone modifications, and small non-coding RNAs (e.g., microRNAs). MicroRNAs (miRNAs) are short, single-stranded RNA that regulate post-transcriptional control of the translation of mRNA. The importance of these epigenetic regulators in controlling developmental processes is becoming clear. However, to date, few studies have investigated the role of miRNAs in toxicological responses limiting knowledge of these critical regulators in mechanisms of toxicity. Atrazine is a herbicide commonly used throughout the Midwestern United States and other areas of the globe for control of weeds in agricultural crops. In certain areas of the United States, atrazine frequently contaminates potable water supplies above the maximum contaminant level of 3 parts per billion (ppb; mg/L) as set by the United States Environmental Protection Agency (U.S. EPA) and is a suspected endocrine disrupting chemical. Studies have begun to investigate the genetic mechanisms of atrazine toxicity; however, studies investigating epigenetic mechanisms are limited. Here we report that expression of both zebrafish and human miRNAs are significantly altered in response to a developmental atrazine exposure of 0.3, 3, or 30 ppb from 1-72 hours post fertilization (hpf). Altered miRNAs are known to play a role in angiogenesis, cancer, or neuronal development, differentiation, and maturation. Targeted analysis of altered human miRNAs with genes previously identified to be altered by atrazine exposure revealed several targets linked to cell cycle and cell signaling. Further analysis of hsa-miRNA-126-3p which had altered expression in all three atrazine treatments at 72 hpf revealed alterations also occurred at 60 hpf in the 30 ppb treatment group. Results from this study indicate miRNA deregulation in zebrafish and human miRNAs following an embryonic atrazine exposure in zebrafish.

Project description:Angiogenesis inhibitors, such as sunitinib, represent a promising strategy to improve glioblastoma (GBM) tumor response. In this study, we used the O6-methylguanine methyltransferase (MGMT)-negative GBM cell line U87MG stably transfected with MGMT (U87/MGMT) to assess whether MGMT expression affects the response to sunitinib. We showed that the addition of sunitinib to standard therapy (temozolomide [TMZ] and radiation therapy [RT]) significantly improved the response of MGMT positive but not of MGMT-negative cells. Gene expression profiling revealed alterations in the angiogenic profile, as well as differential expression of several receptor tyrosine kinases targeted by sunitinib. MGMT-positive cells displayed higher levels of vascular endothelial growth factor receptor 1 (VEGFR-1) compared with U87/EV cells, whereas they displayed decreased levels of VEGFR-2. Depleting MGMT using O6-benzylguanine suggested that the expression of these receptors was directly related to the MGMT status. Also, we showed that MGMT expression was associated with a dramatic increase in the soluble VEGFR-1/VEGFA ratio, thereby suggesting a decrease in bioactive VEGFA and a shift towards an antiangiogenic profile. The reduced angiogenic potential of MGMT-positive cells is supported by: (i) the decreased ability of their secreted factors to induce endothelial tube formation in vitro and (ii) their low tumorigenicity in vivo compared with the MGMT-negative cells. Our study is the first to show a direct link between MGMT expression and decreased angiogenicity and tumorigenicity of GBM cells and suggests the combination of sunitinib and standard therapy as an alternative strategy for GBM patients with MGMT-positive tumors. RNA was isolated from parental U87 (U87_EV) and MGMT-transfected U87 (U87_MGMT) triplicate. Pairwise gene expression differences were compared between the two cell lines. Features selected had more than 2-fold up-or down-regulated (P values of >05, unpaired Studentâs t-test with Bonferroni multiple testing correction) were identified. Database for annotation, visualization, and integrated discovery23 was used to identify enriched gene ontology (GO) biological themes.24 The GO data mining was conducted at a term specificity level 3.25 The EASE score was set at 0.05 and the minimum number of genes in a category was 5.

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Dynamics in zebrafish development define transcriptomic specificity after angiogenesis inhibitor exposure (SU4312)

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