The vascular endothelial thromboxane A2/prostaglandin H2 receptor controls its own activation and impairs angiogenesis via an autocrine cyclooxygenase-2-dependent positive feedback loop.
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ABSTRACT: The thromboxane A2/prostaglandin H2 receptor (TP) plays an eminent role in the pathogenesis of cardiovascular disease and its expression has been reported to increase in the dysfunctional endothelium of cardiovascular high-risk patients. Yet it remains enigmatic in which way the vascular endothelial TP affects angiogenesis. Here we show that increased endothelial TP expression, in the absence of exogenous TP agonists, profoundly inhibits, whereas TP knockdown or endothelial-specific knockout enhance the angiogenic capacity of vascular endothelial cells in vitro and in vivo. Global transcriptome, lipidomic, and functional analyses reveal that the TP induces endothelial cyclooxygenase-2 and downregulates prostacyclin synthase to promote TP ligand release, persistent TP activation, suppression of VEGFR2 expression and inhibition of angiogenesis, effects that are reversed by pharmacological TP inhibition or prostacyclin synthase reconstitution. Further mechanistic analyses reveal that endothelial TP increase cell tension, disturb focal adhesion dynamics and inhibit migration, tube formation and angiogenic sprouting via pathways that enhance endothelial actomyosin contractility. In conclusion, our work uncovers an anti-angiogenic feedback loop by which the TP may disturb angiogenesis and vascular endothelial homeostasis in disease states associated with increased TP expression.
Project description:Endothelial progenitor cells (EPCs) are circulating endothelial precursors shown to incorporate into foci of neovascularisation. Herein, we describe phenotypic characteristics of an EPC sub-type called endothelial colony-forming cells (ECFCs). Peripheral blood-isolated ECFCs expressed endothelial and progenitor surface antigens and displayed cobblestone-patterned colonies with clonal proliferative and angiogenic capacities in vitro. ECFCs demonstrated endothelial cell-like shear stress responses including cell alignment and PECAM-1 expression. Proteomic comparison with an endothelial reference population (human umbilical vein endothelial cells) confirmed a similar proteomic profile. Hierarchical clustering revealed two distinct ECFC clusters with differences in cell growth, proliferation and angiogenesis capacities. The cluster with compromised functionality was also associated with elevated blood pressure and impaired lipid profile. Our findings described an endothelial-like phenotype of blood-derived ECFCs with distinctive proteomic signatures based on cellular and clinical characteristics. ECFCs may aid in identifying novel mechanisms associated with cardiovascular disease risk and new targets to enhance angiogenesis.
Project description:<p>The vasculature represents a highly plastic compartment, capable of switching from a quiescent to an active proliferative state during angiogenesis. Metabolic reprogramming in endothelial cells (ECs) thereby is crucial to cover the increasing cellular energy demand under growth conditions. Here we assess the impact of mitochondrial bioenergetics on neovascularisation, by deleting cox10 gene encoding an assembly factor of cytochrome c oxidase (COX) specifically in mouse ECs, providing a model for vasculature-restricted respiratory deficiency. We show that EC-specific cox10 ablation results in deficient vascular development causing embryonic lethality. In adult mice induction of EC-specific cox10 gene deletion produces no overt phenotype. However, the angiogenic capacity of COX-deficient ECs is severely compromised under energetically demanding conditions, as revealed by significantly delayed wound-healing and impaired tumour growth. We provide genetic evidence for a requirement of mitochondrial respiration in vascular endothelial cells for neoangiogenesis during development, tissue repair and cancer. </p>
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:Angiogenesis and lymphangiogenesis have important roles in cancer progression and chronic inflammatory diseases, but efficient therapies against these diseases have been hampered by the lack of identified vascular lineage-specific markers and growth factors. Using transcriptional profiling of matched pairs of human dermal blood vascular and lymphatic endothelial cells, we first identified 236 lymphatic and 342 blood vascular signature genes. In silico analyses of the biologic pathways associated with these genes revealed lineage-specific functions for each cell type. Using a selection of 85 identified vascular lineage-specific genes, we developed a TaqMan RT-PCR-based, microfluidic card-formatted low-density microvascular differentiation array (LD-MDA) that was used to reliably identify and quantify the degree of lineage-specific differentiation in different types of endothelial cells, and to detect admixture of lymphatic endothelial cells in commercial preparations of microvascular endothelial cells. Application of Prediction Relevance Ranking and analysis of variance of LD-MDA expression profiles of 43 lesional skin samples obtained from patients with the chronic inflammatory disease psoriasis led to identification of cytokines which are significantly associated with angiogenesis or lymphangiogenesis in vivo. In particular, interleukin-7 and fibroblast growth factor-12 were identified as novel (lymph)angiogenic factors. This technology provides a novel tool to quantify lineage-specific vascular differentiation and to characterize (lymph)angiogenesis in clinical samples obtained from angiogenic diseases. This SuperSeries is composed of the following subset Series: GSE11306: Quantification of vascular lineage-specific differentiation (cell type comparison) GSE11307: Quantification of vascular lineage-specific differentiation, psoriasis (chronic inflammation) study Keywords: SuperSeries Refer to individual Series
Project description:Angiogenesis-inhibitor (AI) drugs targeting vascular endothelial growth factor (VEGF) signalling to the endothelial cell (EC) are used to treat various cancers types. However, primary or secondary resistance to therapy is common. Clinical and pre-clinical studies suggest that other alternative pro-angiogenic factors are up-regulated after VEGF-pathway inhibition. Therefore, identification alternative pro-angiogenic pathway(s) is critical for the development of more effective anti-angiogenic therapy. Here we study the role of apelin as a pro-angiogenic G-protein coupled receptor (GPCR) ligand in tumor growth and angiogenesis. We applied single-cell RNA-sequencing to Mouse Lewis lung carcinoma (LLC1) or B16F10 mouse melanoma cell lines (1 X 106) implanted subcutaneously into the flanks of 12 weeks old Apln-/y or littermate control mice in combination with sunitinib or control (vehicle) treatment. We found apelin loss reduced angiogenic sprouting and tip cell marker gene expression in comparison to the sunitinib-alone treated mice and prevented EC tip cell differentiation.
Project description:The receptor tyrosine kinase Mer (gene name Mertk) acts in vascular endothelial cells (ECs) to tighten the blood-brain barrier (BBB) subsequent to viral infection. Correspondingly, we found that Mer regulates the expression and activity of a large cohort of cytoskeletal and BBB proteins, together with endothelial nitric oxide synthase, in brain ECs. We further found that Mer controls the expression of multiple angiogenic genes, and that EC-specific Mertk gene inactivation results in perturbed vascular sprouting and a compromised BBB after induced photothrombotic stroke. Unexpectedly, stroke lesions in the brain were also markedly reduced in the absence of EC Mer, which was linked to reduced plasma expression of fibrinogen, prothrombin, and other effectors of blood coagulation. Together, these results demonstrate that Mer is a central regulator of angiogenesis, BBB integrity, and blood coagulation in the mature vasculature. They may also account for disease severity following infection with the coronavirus SARS-CoV-2.
Project description:Angiogenesis, a process mediating the expansion of vascular beds in many physiological and pathological settings, requires dynamic changes in endothelial cell (EC) behavior. The molecular mechanisms governing EC activity during different phases of vascular growth, remodeling, maturation, and quiescence remain elusive. Here, we have employed actively translating transcriptome analysis of mouse retinal ECs for the characterization of dynamic gene expression changes during postnatal development and the identification of critical angiogenic factors.
Project description:Endothelial cell (EC)-enriched protein coding genes, such as endothelial nitric oxide synthase (eNOS), define quintessential EC-specific physiologic functions. It is not clear whether long noncoding RNAs (lncRNAs) also define cardiovascular cell-type specific phenotypes, especially in the vascular endothelium. Here, we report the existence of a set of EC-enriched lncRNAs and define a role for STEEL (spliced transcript – endothelial enriched lncRNA) in angiogenic potential, macrovascular/microvascular identity and shear stress responsiveness. STEEL is expressed from the terminus of the HOXD locus and is transcribed antisense to HOXD transcription factors. STEEL RNA increases the number and integrity of de novo perfused microvessels in an in vivo model and augments angiogenesis in vitro. The STEEL RNA is polyadenylated, nuclear-enriched and has microvascular predominance. Functionally, STEEL regulates a number of genes in diverse endothelial cells. Of interest, STEEL upregulates both eNOS and the transcription factor Kruppel-like factor 2 (KLF2), and is subject to feedback inhibition by both eNOS and shear-augmented KLF2. Mechanistically, STEEL upregulation of eNOS and KLF2 is transcriptionally mediated, in part, via interaction of chromatin-associated STEEL with the poly-ADP ribosylase, PARP1. For instance, STEEL recruits PARP1 to the KLF2 promoter. This work identifies a role for EC-enriched lncRNAs in the phenotypic adaptation of ECs to both body position and hemodynamic forces, and establishes a newer role for lncRNAs in the transcriptional regulation of EC identity.
Project description:The process of angiogenesis is under complex regulation in adult organisms, particularly as it often occurs in an inflammatory post-wound environment. As such, there are many impacting factors that will regulate the generation of new blood vessels which include not only pro-angiogenic growth factors such as vascular endothelial growth factor, but also angiostatic factors. During initial post-wound hemostasis, a large initial bolus of platelet factor 4 is released into localized areas of damage prior to progression of wound healing toward tissue homeostasis. Due to its early presence and high concentration, the angiostatic chemokine platelet factor 4, which can induce endothelial anoikis, can strongly affect angiogenesis. In our work, we explored signaling crosstalk interactions between vascular endothelial growth factor and platelet factor 4 using phosphotyrosine-enriched mass spectrometry methods on human dermal microvascular endothelial cells cultured under conditions facilitating migratory sprouting into collagen gel matrices. We developed new methods to enable mass spectrometry-based phosphorylation analysis of primary cells cultured on collagen gels, and quantified signaling pathways over the first 48 hours of treatment with vascular endothelial growth factor in the presence or absence of platelet factor 4. By observing early and late signaling dynamics in tandem with correlation network modeling, we found that platelet factor 4 has significant crosstalk with vascular endothelial growth factor by modulating cell migration and polarization pathways, centered around P38α MAPK, Src family kinases Fyn and Lyn, along with FAK. Interestingly, we found EphA2 correlational topology to strongly involve key migration-related signaling nodes after introduction of platelet factor 4, indicating an influence of the angiostatic factor on this ambiguous but generally angiogenic signal in this complex environment.
Project description:Endothelial cells line the inside of all blood vessels forming a single layer of quiescent, non-proliferating cells. While the mechanisms of sprouting angiogenesis, network formation and vascular remodelling are molecularly unravelled in increasing detail, the molecular mechanisms of vascular maturation are still poorly understood. We performed comparative transcriptomic analysis of endothelial cells isolated from infant and adult mice to examine the regulation of angiogenic molecules.