scholarly journals The GEF Trio controls endothelial cell size and arterial remodeling downstream of Vegf signaling in both zebrafish and cell models

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Alina Klems ◽  
Jos van Rijssel ◽  
Anne S. Ramms ◽  
Raphael Wild ◽  
Julia Hammer ◽  
...  

Abstract Arterial networks enlarge in response to increase in tissue metabolism to facilitate flow and nutrient delivery. Typically, the transition of a growing artery with a small diameter into a large caliber artery with a sizeable diameter occurs upon the blood flow driven change in number and shape of endothelial cells lining the arterial lumen. Here, using zebrafish embryos and endothelial cell models, we describe an alternative, flow independent model, involving enlargement of arterial endothelial cells, which results in the formation of large diameter arteries. Endothelial enlargement requires the GEF1 domain of the guanine nucleotide exchange factor Trio and activation of Rho-GTPases Rac1 and RhoG in the cell periphery, inducing F-actin cytoskeleton remodeling, myosin based tension at junction regions and focal adhesions. Activation of Trio in developing arteries in vivo involves precise titration of the Vegf signaling strength in the arterial wall, which is controlled by the soluble Vegf receptor Flt1.

2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Luke Hoeppner ◽  
Sutapa Sinha ◽  
Ying Wang ◽  
Resham Bhattacharya ◽  
Shamit Dutta ◽  
...  

Vascular permeability factor/vascular endothelial growth factor A (VEGF) is a central regulator of angiogenesis and potently promotes vascular permeability. VEGF plays a key role in the pathologies of heart disease, stroke, and cancer. Therefore, understanding the molecular regulation of VEGF signaling is an important pursuit. Rho GTPase proteins play various roles in vasculogenesis and angiogenesis. While the functions of RhoA and RhoB in these processes have been well defined, little is known about the role of RhoC in VEGF-mediated signaling in endothelial cells and vascular development. Here, we describe how RhoC modulates VEGF signaling to regulate endothelial cell proliferation, migration and permeability. We found VEGF stimulation activates RhoC in human umbilical vein endothelial cells (HUVECs), which was completely blocked after VEGF receptor 2 (VEGFR-2) knockdown indicating that VEGF activates RhoC through VEGFR-2 signaling. Interestingly, RhoC knockdown delayed the degradation of VEGFR-2 compared to control siRNA treated HUVECs, thus implicating RhoC in VEGFR-2 trafficking. In light of our results suggesting VEGF activates RhoC through VEGFR-2, we sought to determine whether RhoC regulates vascular permeability through the VEGFR-2/phospholipase Cγ (PLCγ) /Ca 2+ /eNOS cascade. We found RhoC knockdown in VEGF-stimulated HUVECs significantly increased PLC-γ1 phosphorylation at tyrosine 783, promoted basal and VEGF-stimulated eNOS phophorylation at serine 1177, and increased calcium flux compared with control siRNA transfected HUVECs. Taken together, our findings suggest RhoC negatively regulates VEGF-induced vascular permeability. We confirmed this finding through a VEGF-inducible zebrafish model of vascular permeability by observing significantly greater vascular permeability in RhoC morpholino (MO)-injected zebrafish than control MO-injected zebrafish. Furthermore, we showed that RhoC promotes endothelial cell proliferation and negatively regulates endothelial cell migration. Our data suggests a scenario in which RhoC promotes proliferation by upregulating -catenin in a Wnt signaling-independent manner, which in turn, promotes Cyclin D1 expression and subsequently drives cell cycle progression.


2009 ◽  
Vol 296 (5) ◽  
pp. C1162-C1170 ◽  
Author(s):  
Barbara Olszewska-Pazdrak ◽  
Travis W. Hein ◽  
Paulina Olszewska ◽  
Darrell H. Carney

Coronary artery disease results in progressive vascular stenosis associated with chronic myocardial ischemia. Vascular endothelial growth factor (VEGF) stimulates endothelial cell angiogenic responses to revascularize ischemic tissues; however, the effect of chronic hypoxia on the responsiveness of endothelial cells to VEGF remains unclear. We, therefore, investigated whether hypoxia alters VEGF-stimulated signaling and angiogenic responses in primary human coronary artery endothelial (HCAE) cells. Exposure of HCAE cells to hypoxia (1% O2) for 24 h decreased VEGF-stimulated endothelial cell migration (∼82%), proliferation (∼30%), and tube formation. Hypoxia attenuated VEGF-stimulated activation of endothelial nitric oxide (NO) synthase (eNOS) (∼72%) and reduced NO production in VEGF-stimulated cells from 237 ± 38.8 to 61.3 ± 28.4 nmol/l. Moreover, hypoxia also decreased the ratio of phosphorylated eNOS to total eNOS in VEGF-stimulated cells by ∼50%. This effect was not observed in thrombin-stimulated cells, suggesting that hypoxia specifically inhibited VEGF signaling upstream of eNOS phosphorylation. VEGF-induced activation of Akt, ERK1/2, p38, p70S6 kinases, and S6 ribosomal protein was also attenuated in hypoxic cells. Moreover, VEGF-stimulated phosphorylation of VEGF receptor-2 (KDR) at Y996 and Y1175 was decreased by hypoxia. This decrease correlated with a 70 ± 12% decrease in KDR protein expression. Analysis of mRNA from these cells showed that hypoxia reduced steady-state levels of KDR mRNA by 52 ± 16% and decreased mRNA stability relative to normoxic cells. Our findings demonstrate that chronic hypoxia attenuates VEGF-stimulated signaling in HCAE cells by specific downregulation of KDR expression. These data provide a novel explanation for the impaired angiogenic responses to VEGF in endothelial cells exposed to chronic hypoxia.


2008 ◽  
Vol 295 (1) ◽  
pp. H174-H184 ◽  
Author(s):  
Katherine A. Radek ◽  
Elizabeth J. Kovacs ◽  
Richard L. Gallo ◽  
Luisa A. DiPietro

Physiological angiogenesis is regulated by various factors, including signaling through vascular endothelial growth factor (VEGF) receptors. We previously reported that a single dose of ethanol (1.4 g/kg), yielding a blood alcohol concentration of 100 mg/dl, significantly impairs angiogenesis in murine wounds, despite adequate levels of VEGF, suggesting direct effects of ethanol on endothelial cell signaling (40). To examine the mechanism by which ethanol influences angiogenesis in wounds, we employed two different in vitro angiogenesis assays to determine whether acute ethanol exposure (100 mg/dl) would have long-lasting effects on VEGF-induced capillary network formation. Ethanol exposure resulted in reduced VEGF-induced cord formation on collagen and reduced capillary network structure on Matrigel in vitro. In addition, ethanol exposure decreased expression of endothelial VEGF receptor-2, as well as VEGF receptor-2 phosphorylation in vitro. Inhibition of ethanol metabolism by 4-methylpyrazole partially abrogated the effect of ethanol on endothelial cell cord formation. However, mice treated with t-butanol, an alcohol not metabolized by alcohol dehydrogenase, exhibited no change in wound vascularity. These results suggest that products of ethanol metabolism are important factors in the development of ethanol-induced changes in endothelial cell responsiveness to VEGF. In vivo, ethanol exposure caused both decreased angiogenesis and increased hypoxia in wounds. Moreover, in vitro experiments demonstrated a direct effect of ethanol on the response to hypoxia in endothelial cells, as ethanol diminished nuclear hypoxia-inducible factor-1α protein levels. Together, the data establish that acute ethanol exposure significantly impairs angiogenesis and suggest that this effect is mediated by changes in endothelial cell responsiveness to both VEGF and hypoxia.


2016 ◽  
Vol 311 (6) ◽  
pp. C985-C995 ◽  
Author(s):  
Abdullah Al Mamun ◽  
Hisaki Hayashi ◽  
Miho Sakima ◽  
Motohiko Sato

Hypoxia induces angiogenesis through the VEGF signaling pathway; however, signal propagation of VEGF in hypoxia is not fully understood. In this study, we examined alterations in VEGF signaling during hypoxia conditions and its determinant in endothelial cells. To analyze VEGF signaling during hypoxia, human umbilical vein endothelial cells (HUVECs) were exposed to 3 h of hypoxia (1% O2) followed by 3 h of reoxygenation or 12 h of hypoxia. Hypoxia induced expression of VEGF mRNA, but it was not associated with an increase in tube formation by HUVECs. During 3 h of hypoxia, VEGF-induced phosphorylation of VEGF receptor-2 (VEGFR-2) and downstream molecules were significantly inhibited without a change in VEGFR-2 expression, but it was completely restored after reoxygenation. VEGF-mediated VEGFR-2 phosphorylation is associated with a reduction in cellular ATP in hypoxia conditions (65.93 ± 8.32% of normoxia, means ± SE, P < 0.01). Interestingly, attenuation of VEGFR-2 phosphorylation was restored by addition of ATP to prepared membranes from cells that underwent 3 h of hypoxia. In contrast to 3 h of hypoxia, exposure of cells to 12 h of hypoxia decreased VEGFR-2 expression and VEGF-mediated VEGFR-2 phosphorylation. The magnitude of VEGFR-2 phosphorylation was not fully restored by addition of ATP to prepared membranes from cells exposed to 12 h of hypoxia. These data indicate that ATP is an important determinant of VEGF signaling in hypoxia and suggest that the activation process of VEGFR-2 was modified by sustained hypoxia. These observations contribute to our understanding of signal alterations in VEGF in endothelial cells during hypoxia.


2000 ◽  
Vol 113 (1) ◽  
pp. 59-69 ◽  
Author(s):  
M.F. Carlevaro ◽  
S. Cermelli ◽  
R. Cancedda ◽  
F. Descalzi Cancedda

Vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) induces endothelial cell migration and proliferation in culture and is strongly angiogenic in vivo. VEGF synthesis has been shown to occur in both normal and transformed cells. The receptors for the factor have been shown to be localized mainly in endothelial cells, however, the presence of VEGF synthesis and the VEGF receptor in cells other than endothelial cells has been demonstrated. Neoangiogenesis in cartilage growth plate plays a fundamental role in endochondral ossification. We have shown that, in an avian in vitro system for chondrocyte differentiation, VEGF was produced and localized in cell clusters totally resembling in vivo cartilage. The factor was synthesized by hypertrophic chondrocytes and was released into their conditioned medium, which is highly chemotactic for endothelial cells. Antibodies against VEGF inhibited endothelial cell migration induced by chondrocyte conditioned media. Similarly, endothelial cell migration was inhibited also by antibodies directed against the VEGF receptor 2/Flk1 (VEGFR2). In avian and mammalian embryo long bones, immediately before vascular invasion, VEGF was distinctly localized in growth plate hypertrophic chondrocytes. In contrast, VEGF was not observed in quiescent and proliferating chondrocytes earlier in development. VEGF receptor 2 colocalized with the factor both in hypertrophic cartilage in vivo and hypertrophic cartilage engineered in vitro, suggesting an autocrine loop in chondrocytes at the time of their maturation to hypertrophic cells and of cartilage erosion. Regardless of cell exposure to exogenous VEGF, VEGFR-2 phosphorylation was recognized in cultured hypertrophic chondrocytes, supporting the idea of an autocrine functional activation of signal transduction in this non-endothelial cell type as a consequence of the endogenous VEGF production. In summary we propose that VEGF is actively responsible for hypertrophic cartilage neovascularization through a paracrine release by chondrocytes, with invading endothelial cells as a target. Furthermore, VEGF receptor localization and signal transduction in chondrocytes strongly support the hypothesis of a VEGF autocrine activity also in morphogenesis and differentiation of a mesoderm derived cell.


Author(s):  
Steven F. Kemeny ◽  
Alisa Morss Clyne

Endothelial cells line the walls of all blood vessels, where they maintain homeostasis through control of vascular tone, permeability, inflammation, and the growth and regression of blood vessels. Endothelial cells are mechanosensitive to fluid shear stress, elongating and aligning in the flow direction [1–2]. This shape change is driven by rearrangement of the actin cytoskeleton and focal adhesions [2]. Hyperglycemia, a hallmark of diabetes, affects endothelial cell function. High glucose has been shown to increase protein kinase C, formation of glucose-derived advanced glycation end-products, and glucose flux through the aldose reductase pathway within endothelial cells [3]. These changes are thought to be related to increased reactive oxygen species production [4]. While endothelial cell mechanics have been widely studied in healthy conditions, many disease states have yet to be explored. Biochemical alterations related to high glucose may alter endothelial cell mechanics.


2020 ◽  
Vol 11 (10) ◽  
Author(s):  
Ailing Sui ◽  
Xiuping Chen ◽  
Jikui Shen ◽  
Anna M. Demetriades ◽  
Yiyun Yao ◽  
...  

Abstract Activation of the nucleotide-binding domain leucine-rich repeat and pyrin domain containing receptor 3 (NLRP3) inflammasome plays an important role in ocular neovascularization. In our study, we found that the expression and activation levels of NLRP3 inflammasome components, including NLRP3, an apoptosis-associated speck-like protein (ASC) containing caspase activation and recruitment domain (CARD) and caspase-1 (CAS1), were significantly upregulated. In addition, we found interleukin (IL)-1β activity increased while IL-18 activity decreased in the retinas of oxygen-induced ischemic retinopathy (OIR) mice. MCC950, an inhibitor of NLRP3, reversed the IL-1β/IL-18 activation pattern, inhibited the formation of retinal neovascularization (RNV), decreased the number of acellular capillaries and reduced leakage of retinal vessels. Moreover, MCC950 could regulate the expression of endothelial cell- and pericyte function-associated molecules, such as vascular endothelial growth factor (VEGF), VEGF receptor (VEGFR)1, VEGFR2, matrix metalloproteinase (MMP)2, MMP9, tissue inhibitor of metalloproteinases (TIMP)1, TIMP2, platelet-derived growth factor receptor-β (PDGFR-β), platelet-derived growth factor-B (PDGF-B), and angiopoietin2 (Ang2). In vitro, recombinant human (r)IL-18 and rIL-1β regulated the expression of endothelial cell- and pericyte function-associated molecules and the proliferation and migration of endothelial cells and pericytes. We therefore determined that inhibiting the NLRP3 inflammasome with MCC950 can regulate the function of endothelial cells and pericytes by reversing the IL-1β/IL-18 activation pattern to ameliorate RNV and leakage; thereby opening new avenues to treat RNV-associated ocular diseases.


2000 ◽  
Vol 84 (08) ◽  
pp. 325-331 ◽  
Author(s):  
M. J. B. Wissink ◽  
M. J. A. van Luyn ◽  
R. Beernink ◽  
F. Dijk ◽  
A. A. Poot ◽  
...  

SummaryEndothelial cell seeding, a promising method to improve the performance of small-diameter vascular grafts, requires a suitable substrate, such as crosslinked collagen. Commonly used crosslinking agents such as glutaraldehyde and formaldehyde cause, however, cytotoxic reactions and thereby hamper endothelialization of currently available collagen-coated vascular graft materials.The aim of this study was to investigate the effects of an alternative method for crosslinking of collagen, using N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide (EDC) in combination with N-hydroxysuccinimide (NHS), on various cellular functions of human umbilical vein endothelial cells (HUVECs) in vitro. Compared to non-crosslinked type I collagen, proliferation of seeded endothelial cells was significantly increased on EDC/NHS-crosslinked collagen. Furthermore, higher cell numbers were found with increasing crosslink densities. Neither the morphology of the cells nor the secretion of prostacyclin (PGI2), von Willebrand factor (vWF), tissue plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI-1) was affected by the crosslink density of the collagen substrate. Therefore, EDC/NHScrosslinked collagen is candidate substrate for in vivo application such as endothelial cell seeding of collagen-coated vascular grafts.


Blood ◽  
2006 ◽  
Vol 107 (3) ◽  
pp. 931-939 ◽  
Author(s):  
Cassin Kimmel Williams ◽  
Ji-Liang Li ◽  
Matilde Murga ◽  
Adrian L. Harris ◽  
Giovanna Tosato

AbstractDelta-like 4 (Dll4), a membrane-bound ligand for Notch1 and Notch4, is selectively expressed in the developing endothelium and in some tumor endothelium, and it is induced by vascular endothelial growth factor (VEGF)-A and hypoxia. Gene targeting studies have shown that Dll4 is required for normal embryonic vascular remodeling, but the mechanisms underlying Dll4 regulatory functions are currently not defined. In this study, we generated primary human endothelial cells that overexpress Dll4 protein to study Dll4 function and mechanism of action. Human umbilical vein endothelial cells retrovirally transduced with Dll4 displayed reduced proliferative and migratory responses selectively to VEGF-A. Expression of VEGF receptor-2, the principal signaling receptor for VEGF-A in endothelial cells, and coreceptor neuropilin-1 was significantly decreased in Dll4-transduced endothelial cells. Consistent with Dll4 signaling through Notch, expression of HEY2, one of the transcription factors that mediates Notch function, was significantly induced in Dll4-overexpressing endothelial cells. The γ-secretase inhibitor L-685458 significantly reconstituted endothelial cell proliferation inhibited by immobilized extracellular Dll4 and reconstituted VEGFR2 expression in Dll4-overerexpressing endothelial cells. These results identify the Notch ligand Dll4 as a selective inhibitor of VEGF-A biologic activities down-regulating 2 VEGF receptors expressed on endothelial cells and raise the possibility that Dll4 may be exploited therapeutically to modulate angiogenesis.


Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2300-2300
Author(s):  
Karen A Breen ◽  
Kiran Parmar ◽  
Beverley J Hunt

Abstract Abstract 2300 Background: The antiphospholipid syndrome (APS) is characterised by presence of persistent antiphospholipid antibodies in association with thrombosis and/or pregnancy morbidity and mortality. Activation of endothelial cells by aPL has been proposed to pay a role in the pathogenesis of APS;antiphospholipid antibodies(aPL) activate endothelial cells in vitro and some evidence of endothelial cell perturbation has been found in patients with aPL. Vascular endothelial growth factor(VEGF) promotes endothelial cell growth and angiogenesis and has been shown to upregulate tissue factor(TF), and elevated VEGF levels have been found to correlate with elevated TF levels in APS. Soluble FMS like tyrosine kinase −1(SLFT-1) and soluble Endoglin(sENG) are antiangiogenic proteins. sFLT1 is a variant of the VEGF receptor released by endothelial cells and monocytes, binds VEGF causing endothelial dysfunction and decreased angiogenesis. sENG is a TGFβ co-receptor which impairs TGF β1 receptor binding and its downstream signalling effects. sFLT-1 and sENG are implicated in the pathogenesis of pre-eclampsia, and are elevated in disorders associated with endothelial dysfunction such as sickle cell disease, chronic kidney disease and coronary artery disease, but have not been studied in patients with aPL. Aims: The aim of this study was to measure sFLT1, sENG, sTF and VEGF in patients with aPL. Materials & methods: Local ethics committee approval was obtained and samples were taken from 182 patients (175 females, 7 males, median age 42 (range 19–73) years) who had PAPS, or had persistent aPL without associated complications. 28 healthy controls (28 females, median age (range 20–58) years) were included. Patients with PAPS included 95 with thrombotic complications, 48 with obstetric complications and 39 with isolated aPL. Patients with intercurrent infection or malignancy were excluded and the control group were not known to have aPL. Blood was drawn into Vacutainers containing EDTA 0.105M and processed within 3 hours of collection. ELISA assays measuring sFLT1, sENG, VEGF and sTF levels were performed according to manufacturer's protocol (Quidel, Pathway diagnostics ltd., Dorking, UK). Intra-assay CV for sFLT1,sENG, VEGF and sTF was 3.0,3.3,4.8 and 6.0 respectively. Inter assay CV for sFLT1,sENG, VEGF and sTF was 6.5,7.6, 7.4 and 5.0 respectively. Statistical analysis of results was performed using the Stata-11 software statistical package. Logarithmic transformation of data was performed and differences between groups were compared using linear regression methods, adjusting for age, ethnicity and medications. Results: Results are shown below in table 1 and are described as means and 95% confidence intervals (adjusted for age, sex, ethnicity and medications). sFLT1 and sENG levels were significantly higher in patients with aPL/PAPS compared to healthy controls(p<0.05). TF levels were significantly lower in patients with aPL/PAPS compared to healthy controls(p<0.05). There were no significant differences in VEGF levels in patients with aPL compared to controls(regardless of complication). When patients were categorised according to aPL related complication (thrombotic APS, obstetric aPS, isolated aPL), sFLT1 and sENG levels were found to be significantly higher in patients with thrombotic APS(p<0.05) compared to controls, sFLT1 levels were also significantly elevated in obstetric APS. TF levels were significantly lower in patients with obstetric APS and isolated aPL compared to controls. There were no differences between patients with aPL and controls when means were adjusted for age, ethnicity or medications. sFLT1 was associated with the presence of aPL/PAPS(area under ROC=0.76), whereas sENG had a weaker association (area under ROC: 0.65). Conclusions: We have demonstrated evidence of increased levels of sENG and sFLT1 in patients with aPL/PAPS.This suggests that there is underlying endothelial dysfunction in patients with APS. The role of sENG and sFLT1 in the pathogenesis of APS requires further exploration. Disclosures: No relevant conflicts of interest to declare.


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