Project description:Dilated cardiomyopathy is a frequently occurring human disease compromising heart function and a major cause of cardiac death. The causes of cardiomyopathies are often unknown. There is increasing evidence indicating that endothelial cells lining blood vessels control the homeostasis of various organs, but the special properties and functional roles of the vasculature in the adult heart maintain remain little understood. Here, we have used mouse genetics, imaging and cell biology approaches to investigate how vascular homeostasis in the adult heart is controlled by EphB4 and its ligand ephrin-B2, which are known regulators of sprouting angiogenesis, vascular morphogenesis and arteriovenous differentiation during development. We show that inducible and endothelial cell-specific inactivation of the Ephb4 gene in adult mice is compatible with survival, but leads to rupturing of cardiac capillaries, cardiomyocyte hypertrophy, and pathological cardiac remodelling. In contrast, EphB4 is not required for the integrity and homeostatic function of capillaries in skeletal muscle. Our analysis of mutant mice and cultured endothelial cells shows that EphB4 controls the function of caveolae, cell-cell adhesion under mechanical stress and lipid transport. Together, our findings establish that EphB4 maintains critical functional properties of the adult cardiac vasculature and thereby prevents dilated cardiomyopathy-like defects.
Project description:Given that the Nes-gfp allele specifically labels coronary ECs, endogenous GFP and the endomucin marker (which was highly expressed in endocardial cells) were used together to separate endocardial and coronary vascular endothelial cell subpopulations in different developmental stages
Project description:The cytochrome P450 reductase (POR) transfers electrons to all microsomal cytochrome P450 enzymes (CYP450) thereby driving their activity. In the vascular system, the POR/CYP450 system has been linked to the production of epoxyeicosatrienoic acids (EETs) but also to the generation of reactive oxygen species. In cardiac myocytes (CMs), EETs have been shown to modulate the cardiac function and have cardioprotective effects. The functional importance of the endothelial POR/CYP450 system in the heart is unclear and was studied here using endothelial cell-specific, inducible knockout mice of POR (ecPOR-/-). RNA sequencing of murine cardiac cells revealed a cell type-specific expression of different CYP450 homologues. Cardiac endothelial cells mainly expressed members of the CYP2 family which produces EETs, and of the CYP4 family that generates omega fatty acids. Tamoxifen-induced endothelial deletion of POR in mice led to cardiac remodelling under basal conditions, as shown by an increase in heart weight to body weight ratio and an increased CM area as compared to control animals. Endothelial deletion of POR was associated with a significant increase in endothelial genes linked to protein synthesis with no changes in genes of the oxidative stress response. CM of ecPOR-/- mice exhibited attenuated expression of genes linked to mitochondrial function and an increase in genes related to cardiac myocyte contractility. In a model of pressure overload (transverse aortic constriction, TAC with O-rings), ecPOR-/- mice exhibited an accelerated reduction in cardiac output (CO) and stroke volume (SV) as compared to control mice. These results suggest that loss of endothelial POR along with a reduction in EETs leads to an increase in vascular stiffness and loss in cardioprotection, resulting in cardiac remodelling.
Project description:Interactions of cancer cells with the vasculature are essential for tumor growth and likely promote metastatic progression. Endothelial cell content and lympho-vascular invasion are generally associated with tumor aggressiveness, however, these features are generally not employed in the clinic. We aimed to determine if endothelial cell gene expression signatures could be utilized to better characterize breast tumor biology, and to establish if vascular cell-derived signatures could provide information to predict tumors likely to metastasize. Here we report on the identification of a gene signature for vascular endothelial cells, and a second for cancer-activated vasculature. Both signatures independently identify subsets of aggressive breast cancers. Interestingly, the vascular content signature and a previously identified hypoxia signature both provide prognostic information beyond currently utilized clinical parameters and intrinsic subtype classifications. In these studies, we also examined the relationship that the breast cancer subtypes have with vascular gene expression profiles, and found that claudin-low tumors and cell lines express vascular gene expression profiles and displayed endothelial-like tube formation when grown in three-dimensions. These findings are directly applicable to clinical care and therapeutic treatment design as they identify highly aggressive subsets of tumors with genetic and morphologic vascular properties. reference x sample
Project description:Endothelial cell dysfunction plays an essential role in the process of cardiac ischemia-reperfusion (I/R) injury. Mitochondria damage, which can trigger inflammasome activation and subsequent pyroptosis, perturbs endothelial homeostasis, leading to aggravated cardiac I/R injury. Sphingosine 1-phosphate (S1P), a bioactive lipid molecule, exerts multifaceted effect on I/R injury via its different S1P receptors. However, the effect of EC-expressing S1P receptors on endothelial dysfunction, mitochondrial damage-induced inflammasome activation and consequent pyroptosis during cardiac I/R injury remain unclear. Our findings suggest a pivotal role of EC-expressing S1PR2 to control EC mitochondrial homeostasis and demonstrate that S1PR2-meidated mitochondrial dysfunction can trigger inflammasome activation and pyroptosis in ECs, which significantly influences inflammatory responses and heart injuries following I/R.
Project description:Precise vascular patterning is critical for normal growth and development. The ERG transcription factor drives Delta like ligand 4 (DLL4)/Notch signalling and is thought to act as pivotal regulators of endothelial cell (EC) dynamics and developmental angiogenesis. However, molecular regulation of ERG activity remains obscure. Using a series of EC specific Focal Adhesion Kinase (FAK)-knockout (KO) and point-mutant FAK-knockin mice, we show that loss of ECFAK, its kinase activity or phosphorylation at FAK-Y397, but not FAK-Y861, reduces ERG and DLL4 expression levels together with concomitant aberrations in vascular patterning. Rapid Immunoprecipitation Mass Spectrometry of Endogenous Proteins identified that endothelial nuclear-FAK interacts with the de-ubiquitinase USP9x and the ubiquitin ligase TRIM25 enzymes. Further in silico analysis corroborates that ERG interacts with USP9x and TRIM25. Moreover, ERG levels are reduced in FAKKO ECs via a ubiquitin-mediated post-translational modification programme involving USP9x and TRIM25. Re-expression of ERG in vivo and in vitro rescues the aberrant vessel sprouting defects observed in the absence of ECFAK. Our findings identify ECFAK as a regulator of retinal vascular patterning by controlling ERG protein degradation via TRIM25/USP9x.
Project description:Endothelial cell dysfunction plays an essential role in the process of cardiac ischemia-reperfusion (I/R) injury. Mitochondria damage, which can trigger inflammasome activation and subsequent pyroptosis, perturbs endothelial homeostasis, leading to aggravated cardiac I/R injury. Sphingosine 1-phosphate (S1P), a bioactive lipid molecule, exerts multifaceted effect on I/R injury via its different S1P receptors. However, the effect of EC-expressing S1P receptors on endothelial dysfunction, mitochondrial damage-induced inflammasome activation and consequent pyroptosis during cardiac I/R injury remain unclear. Our findings suggest a pivotal role of EC-expressing S1PR2 to control EC mitochondrial homeostasis and demonstrate that S1PR2-meidated mitochondrial dysfunction can trigger inflammasome activation and pyroptosis in ECs, which significantly influences inflammatory responses and heart injuries following I/R.
Project description:Dysfunction of vascular endothelium is characteristic of many aging-related diseases, including Alzheimers disease (AD) and AD-related dementias (ADRD). While it is widely posited that endothelial cell dysfunction contributes to the pathogenesis and/or progression of AD/ADRD, it is not clear how. A plausible hypothesis is that intercellular trafficking of extracellular vesicles (EVs) from senescent vascular endothelial cells promotes vascular endothelial cell dysfunction. To test this hypothesis, we compared the expression of proteins and miRNAs in EVs isolated from early passage (EP) vs. senescent (SEN) primary human coronary artery endothelial cells (HCAECs) from the same donor. Proteomics and miRNA libraries constructed from these EV isolates were evaluated using FunRich gene ontology analysis to compare functional enrichment between EP and SEN endothelial cell EVs (ECEVs). Replicative senescence was associated with altered EV abundance and contents independent of changes in EV size. Unique sets of miRNAs and proteins were differentially expressed in SEN-ECEVs, including molecules related to cell adhesion, barrier integrity, receptor signaling, endothelial-mesenchymal transition and cell senescence. miR-181a-5p was the most upregulated miRNA in SEN-ECEVs, increasing >5-fold. SEN-ECEV proteomes supported involvement in several pro-inflammatory pathways consistent with senescence and the senescence-associated secretory phenotype (SASP). These data indicate that SEN-ECEVs are enriched in bioactive molecules implicated in senescence-associated vascular dysfunction, blood-brain barrier impairment, and AD/ADRD pathology. These observations suggest involvement of SEN-ECEVs in the pathogenesis of vascular dysfunction associated with AD/ADRD.