Project description:To identify previously unknown determinants of endothelial cell sprouting, we defined and exploited a pharmacological strategy for the manipulation of angiogenic cell behavior in vivo. Whereas high vascular endothelial growth factor receptor (Vegfr) signaling is known to promote tip cell (TC) specification, activation of the Notch receptor via its ligand Delta-like 4 (Dll4) represses the TC phenotype to promote stalk cell (SC) fate. Conversely, suppression of Notch activity upon antagonistic interaction with its ligand Jagged1 pro- motes TC formation. Hence, specification of TCs involves tight spatiotemporal control of Vegfr/Notch signaling. Consequently, we hypothesized that the pharmacological manipulation of Vegfr/Notch signaling selectively during zebrafish intersegmental vessel (ISV) angiogenesis would enable the precise control of angiogenic EC behavior and sprouting- associated gene expression in vivo. For more information, see Herbert et al., 2012, PMID 22921365.
Project description:In the tumor microenvironment the extracellular matrix molecule tenascin-C is highly expressed which correlates with worsened survival prognosis. Tenascin-C promotes multiple steps in cancer progression. In particular, tenascin-C promotes the tumor angiogenic switch and the formation of more but poorly functional blood vessels by ill defined mechanisms. Here, we studied tenascin-C angio-modulatory functions by tumor and stromal cells. Unexpectedly, we observed that direct contact of endothelial cells with tenascin-C impairs angiogenesis through disruption of actin polymerization. This resulted in cytoplasmic retention of the F-actin sensor and co-transcription factor YAP and led to downregulation of YAP pro-angiogenic target genes. Conversely, tumor cells and carcinoma associated fibroblasts exposed to tenascin-C secreted pro-angiogenic factors that promoted endothelial cell survival and tubulogenesis. We identified and functionally validated CXCL12 and Ephrin- B2 as important pro-angiogenic effectors of tenascin-C. Proteomic analysis of the secretome of tumor cells exposed to tenascin-C revealed a signature that predicts shorter survival of patients with low grade glioma and glioblastoma with a particular significance for a combined expression of tenascin-C and Ephrin-B2. Altogether, we demonstrated a dual mechanism of action of tenascin-C in tumor angiogenesis where direct contact of endothelial cells with tenascin-C impairs angiogenesis, and paracrine signals derived from contact of tumor cells and carcinoma associated fibroblasts with tenascin-C promotes angiogenesis. These opposing effects provide for the first time an explanation of divergent mechanisms controlled by tenascin-C which can result in a denser but less functional tumor blood vasculature and might unveil new targeting and prediction opportunities.
Project description:Several environmental pollutants have been reported to exhibit either pro-angiogenic or anti-angiogenic effects, which may contribute to related vascular diseases. However, the specific mechanism by which pollutants induce sprouting angiogenesis is unclear, and there are few studies on the association between the site of hyperangiogenesis and vascular diseases. In this study, zebrafish were exposed to bisphenol S (BPS, 1~100 µg/L) and tetrabromobisphenol S (TBBPS, 0.1 and 10 µg/L) from the embryonic to the larval stage to investigate how pollutants interfere with the function of ectopic sprouting vessels. Results showed that BPS and TBBPS promoted ectopic sprouting angiogenesis in different types of vascular plexus at different developmental time points but inhibited vascular endothelial-cadherin (VE-cadherin) expression. The proteomic analyses on eGFP-positive endothelial cells isolated from Tg(flk1: eGFP) zebrafish indicated that both BPS and TBBPS induced ectopic angiogenesis through inhibiting VE-cadherin-mediated adherens junction and activating the downstream pro-angiogenic signaling. In ectopic sprouting vessels induced by BPS and TBBPS, an increased endothelial permeability resulted in white blood cells recruitment and erythrocyte retention. Human oxidized lipids were also prone to deposit in these ectopic vessels following BPS and TBBPS exposure. This suggests that ectopic angiogenesis is a cause of vascular dysfunction and related diseases.
Project description:To determine whether dural fibroblasts (DuF) under IL-1β-mediated wound conditions, release pro-angiogenic factors, and promote angiogenic properties in human endothelial cells (ECs). DuF were stimulated by pro-inflammatory cytokines interleukin (IL)-1β, and transcriptome sequencing was then used to identify the differentially expressed genes in the DuF with/without IL-1β stimulation (DuFCon/DuFIL1b)
Project description:Anti-angiogenic anticancer therapies possess immune-stimulatory properties by counteracting pro-angiogenic molecular mechanisms. We report that tumor endothelial cells ubiquitously overexpress and secrete the intermediate filament protein vimentin through type III unconventional mechanisms. Extracellular vimentin is pro-angiogenic and functionally mimics VEGF action, while concomitantly acting as inhibitor of leukocyte-endothelial interactions. Targeting of extracellular vimentin presents a promising anti-angiogenic immunotherapy strategy against cancer. Here we describe profiling of the HUVEC (Human Umbilical Vein Endothelial Cell) proteome, with special emphasis on vimentin (variants) in the different fractions. We have evidence that vimentin is externalized and deposited in the matrix of cultured cells and is as such available for targeted antiangiogenic therapeutics. The aim of the experiment is to determine the protein variants of vimentin in the cell, the secretome, and in the matrix deposited by the cells.
Project description:Class IIa histone deacetylases (HDACs) are signal-responsive regulators of gene expression involved in vascular homeostasis. To investigate the differential role of class IIa HDACs for the regulation of angiogenesis, we used siRNA to specifically suppress the individual HDAC isoenzymes. Among the HDAC isoforms tested, silencing of HDAC5 exhibited a unique pro-angiogenic effect evidenced by increased endothelial cell migration, sprouting and tube formation. Consistently, overexpression of HDAC5 decreased sprout formation, indicating that HDAC5 is a negative regulator of angiogenesis. The anti-angiogenic activity of HDAC5 was independent of MEF2 binding and its deacetylase activity, but required a nuclear localization indicating that HDAC5 might affect the transcriptional regulation of gene expression. To identify putative HDAC5 targets, we performed microarray expression analysis. Silencing of HDAC5 increased the expression of fibroblast growth factor 2 (FGF2) and angiogenic guidance factors including Slit2. Antagonization of FGF2 or Slit2 reduced sprout induction in response to HDAC5 siRNA. ChIP assays demonstrate that HDAC5 binds to the promoter of FGF2 and Slit2. In summary, HDAC5 represses angiogenic genes, like FGF2 and Slit2, which causally contribute to capillary-like sprouting of endothelial cells. The de-repression of angiogenic genes by HDAC5 inactivation may provide a useful therapeutic target for induction of angiogenesis.
Project description:Alzheimer’s disease (AD) is the most common form of dementia but has no effective treatment. A comprehensive investigation of cell-type-specific responses and cellular heterogeneity in AD is required to provide precise molecular and cellular targets for therapeutic development. Accordingly, we perform single-nucleus transcriptome analysis of 169,496 nuclei from the prefrontal cortical samples of AD patients and normal control (NC) subjects. Differential analysis shows that the cell-type-specific transcriptomic changes in AD are associated with the disruption of biological processes including angiogenesis, immune activation, synaptic signaling, and myelination. Subcluster analysis reveals that compared to NC brains, AD brains contain fewer neuroprotective astrocytes and oligodendrocytes. Importantly, our findings show that a subpopulation of angiogenic endothelial cells is induced in the brain in patients with AD. These angiogenic endothelial cells exhibit increased expression of angiogenic growth factors and their receptors (i.e., EGFL7, FLT1, and VWF) and antigen-presentation machinery (i.e., B2M and HLA-E). This suggests that these endothelial cells contribute to angiogenesis and immune response in AD pathogenesis. Thus, our comprehensive molecular profiling of brain samples from patients with AD reveals previously unknown molecular changes as well as cellular targets that potentially underlie the functional dysregulation of endothelial cells, astrocytes, and oligodendrocytes in AD, providing important insights for therapeutic development.
Project description:Background: The tumor microenvironment (TME) represents a promising avenue to understand gonadotroph tumors and develop therapeutic tools. Here, we aimed to gain insight into the tumorigenesis mechanisms driven by the gonadotoph TME. Methods: Single-cell and spatial-omics were combined with histological analysis. Mice engrafted with tumor cells were used for functional validation. Results: using single-cell and spatial transcriptomic data from gonadotroph tumors and normal tissues, we identified mast cells in the microenvironment of gonadotroph tumors and confirmed their physical and functional interaction with endothelial cells. Quantification of mast cells in 40 patients suggested their pro-tumoral role as tumors relapsing after surgery harbored more mast cells. More interestingly, the distribution of mast cells was associated with the presence of a higher number of blood vessels, with an increased microvessel density (MVD), and with blood vessels with thicker walls. Ligand-receptor network analysis highlighted VEGFA as a modulator of mast/endothelial cell communication, a result confirmed by the identification of intratumoral mast cells expressing VEGFA in mouse and human gonadotroph tumors. Finally, using mice engrafted with gonadotroph tumor cells, we demonstrated that the depletion of mast cells reduces tumor volume through increased apoptosis. These observations were associated with increased hemorrhagic areas and a significant reduction of the number of blood vessels and MVD as evidenced in human gonadotroph tumors. Conclusion: we demonstrate that mast cells represent a new actor of the gonadotroph TME, and highlight their pro-angiogenic and pro-tumorigenic roles as potential targets for the therapeutic treatment of gonadotroph tumors.