Endothelial cell mineralocorticoid receptors oppose VEGF-induced gene expression and angiogenesis

Aldosterone is a key factor in adverse cardiovascular remodeling by acting on the mineralocorticoid receptor (MR) in different cell types. Endothelial MR activation mediates hypertrophy, inflammation and fibrosis. Cardiovascular remodeling is often accompanied by impaired angiogenesis, which is a risk factor for the development of heart failure. In this study, we evaluated the impact of MR in endothelial cells on angiogenesis. Deoxycorticosterone acetate (DOCA)-induced hypertension was associated with capillary rarefaction in the heart of WT mice but not of mice with cell type-specific MR deletion in endothelial cells. Consistently, endothelial MR deletion prevented the inhibitory effect of aldosterone on the capillarization of subcutaneously implanted silicon tubes and on capillary sprouting from aortic ring segments. We examined MR-dependent gene expression in cultured endothelial cells by RNA-seq and identified a cluster of differentially regulated genes related to angiogenesis. We found opposing effects on gene expression when comparing activation of the mineralocorticoid receptor in ECs to treatment with vascular endothelial growth factor (VEGF), a potent activator of angiogenesis. In conclusion, we demonstrate here that activation of endothelial cell MR impaired angiogenic capacity and lead to capillary rarefaction in a mouse model of MR-driven hypertension. MR activation opposed VEGF-induced gene expression leading to the dysregulation of angiogenesis-related gene networks in endothelial cells. Our findings underscore the pivotal role of endothelial cell MR in the pathophysiology of hypertension and related heart disease.

Extracellular bone morphogenetic protein modulator BMPER and twisted gastrulation homolog 1 preserve arterial-venous specification in zebrafish blood vessel development and regulate Notch signaling in endothelial cells

The bone morphogenetic protein (BMP) signaling pathway plays a central role during vasculature development. Mutations or dysregulation of the BMP pathway members have been linked to arteriovenous malformations. In the present study, we investigated the effect of the BMP modulators bone morphogenetic protein endothelial precursor-derived regulator (BMPER) and twisted gastrulation protein homolog 1 (TWSG1) on arteriovenous specification during zebrafish development and analyzed downstream Notch signaling pathway in human endothelial cells. Silencing of bmper and twsg1b in zebrafish embryos by morpholinos resulted in a pronounced enhancement of venous ephrinB4a marker expression and concomitant dysregulated arterial ephrinb2a marker expression detected by in situ hybridization. As arteriovenous specification was disturbed, we assessed the impact of BMPER and TWSG1 protein stimulation on the Notch signaling pathway on endothelial cells from different origin. Quantitative real-time PCR (qRT-PCR) and western blot analysis showed increased expression of Notch target gene hairy and enhancer of split, HEY1/2 and EPHRINB2. Consistently, silencing of BMPER in endothelial cells by siRNAs decreased Notch signaling and downstream effectors. BMP receptor antagonist DMH1 abolished BMPER and BMP4 induced Notch signaling pathway activation. In conclusion, we found that in endothelial cells, BMPER and TWSG1 are necessary for regular Notch signaling activity and in zebrafish embryos BMPER and TWSG1 preserve arteriovenous specification to prevent malformations.

The neuronal transcription factor NPAS4 is a strong inducer of sprouting angiogenesis and tip cell formation

RATIONALE

Regarding branching morphogenesis, neurogenesis and angiogenesis share common principle mechanisms and make use of the same molecules. Therefore, the investigation of neuronal molecules involved in vascular morphogenesis provides new possibilities for pro-angiogenic approaches in cardiovascular diseases.

OBJECTIVE

In this study, we investigated the role of the neuronal transcription factor NPAS4 in angiogenesis.

METHODS AND RESULTS

Here, we demonstrate that the neuronal transcription factor NPAS4 is expressed in endothelial cells of different origin using reverse transcription PCR and western blot analysis. To investigate how NPAS4 affects endothelial cell function, NPAS4 was overexpressed by plasmid transfection or depleted from human umbilical vein endothelial cells (HUVECs) by specific siRNAs. In vitro HUVEC sprouting assays showed that sprouting and branching of endothelial cells was enhanced by NPAS4 overexpression. Consistently, silencing of NPAS4 resulted in reduced HUVEC sprouting and branching. Mechanistically, we identified as target gene vascular endothelial adhesion molecule VE-cadherin to be involved in the pro-angiogenic function of NPAS4. In endothelial cell mosaic spheroid sprouting assays, NPAS4 was involved in tip cell formation. In vivo experiments in mouse and zebrafish confirmed our in vitro findings. NPAS4-deficient mice displayed reduced ingrowth of endothelial cells in the Matrigel plug assay. Consistent with a regulatory role of NPAS4 in endothelial cell function silencing of NPAS4 in zebrafish by specific morpholinos resulted in perturbed intersegmental vessels growth.

CONCLUSIONS

NPAS4 is expressed in endothelial cells, regulates VE-cadherin expression and regulates sprouting angiogenesis.