scholarly journals Meningeal lymphatic endothelial cells fulfill scavenger endothelial cell function and employ Mrc1a for cargo uptake

2019 ◽  
Author(s):  
Yvonne Padberg ◽  
Andreas van Impel ◽  
Max van Lessen ◽  
Jeroen Bussmann ◽  
Stefan Schulte-Merker

AbstractBrain lymphatic endothelial cells (BLECs) constitute a group of loosely connected endothelial cells within the meningeal layer of the zebrafish brain. We previously reported that BLECs efficiently endocytose extracellular cargo molecules (van Lessen et al., 2017), but how this is accomplished and controlled on the molecular level remains unclear. We here compare BLECs to scavenging endothelial cells (SECs) in the embryonic cardinal vein and find them to accept an identical set of substrate molecules. While there is redundancy in the type of scavenger receptors being used, the two cell populations rely for specific substrate molecules on different cell surface receptors to mediate their physiological role: Stab2 appears more critical within SECs in the cardinal vein, while BLECs depend more on the Mrc1a receptor for internalization of cargo. Given the striking similarities to the substrate specificity of cardinal vein SECs, we postulate that BLECs qualify functionally as SECs of the brain.

2021 ◽  
Vol 22 (11) ◽  
pp. 5635
Author(s):  
Katharina Urschel ◽  
Miyuki Tauchi ◽  
Stephan Achenbach ◽  
Barbara Dietel

In the 1900s, researchers established animal models experimentally to induce atherosclerosis by feeding them with a cholesterol-rich diet. It is now accepted that high circulating cholesterol is one of the main causes of atherosclerosis; however, plaque localization cannot be explained solely by hyperlipidemia. A tremendous amount of studies has demonstrated that hemodynamic forces modify endothelial athero-susceptibility phenotypes. Endothelial cells possess mechanosensors on the apical surface to detect a blood stream-induced force on the vessel wall, known as “wall shear stress (WSS)”, and induce cellular and molecular responses. Investigations to elucidate the mechanisms of this process are on-going: on the one hand, hemodynamics in complex vessel systems have been described in detail, owing to the recent progress in imaging and computational techniques. On the other hand, investigations using unique in vitro chamber systems with various flow applications have enhanced the understanding of WSS-induced changes in endothelial cell function and the involvement of the glycocalyx, the apical surface layer of endothelial cells, in this process. In the clinical setting, attempts have been made to measure WSS and/or glycocalyx degradation non-invasively, for the purpose of their diagnostic utilization. An increasing body of evidence shows that WSS, as well as serum glycocalyx components, can serve as a predicting factor for atherosclerosis development and, most importantly, for the rupture of plaques in patients with high risk of coronary heart disease.


2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Qi Sun ◽  
Dongcao Lv ◽  
Qiulian Zhou ◽  
Yihua Bei ◽  
Junjie Xiao

MicroRNAs (miRNAs, miRs), endogenous small non-coding RNA, have been shown to act as essential regulators in angiogenesis which plays important roles in improving blood flow and cardiac function following myocardial infarction. The current study investigated the potential of miR-4260 in endothelial cell function and angiogenesis using human umbilical vein endothelial cells (HUVEC). Our data demonstrated that overexpression of miR-4260 was associated with increased proliferation and migration of HUVEC using EdU incorporation assay (17.25%±1.31 vs 25.78%±1.24 in nc-mimics vs miR-4260 mimics, respectively) and wound healing assay, respectively. While downregulation of miR-4260 inhibited the proliferation (17.90%±1.37 vs 10.66%±1.41 in nc-inhibitor vs miR-4260 inhibitor, respectively) and migration of HUVEC. Furthermore, we found that miR-4260 mimics increased (129.75±3.68 vs 147±3.13 in nc-mimics vs miR-4260 mimics, respectively), while miR-4260 inhibitor decreased the tube formation of HUVECs in vitro (123.25±2.17 vs 92±4.45 in nc-inhibitor vs miR-4260 inhibitor expression, respectively). Our data indicate that miR-4260 contributes to the proliferation, migration and tube formation of endothelial cells, and might be essential regulators for angiogenesis. Further study is needed to investigate the underlying mechanism that mediates the role of miR-4260 in angiogenesis by identifying its putative downstream target genes.


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.


Blood ◽  
2010 ◽  
Vol 116 (17) ◽  
pp. 3356-3366 ◽  
Author(s):  
Karlien Hermans ◽  
Filip Claes ◽  
Wouter Vandevelde ◽  
Wei Zheng ◽  
Ilse Geudens ◽  
...  

Abstract The molecular basis of lymphangiogenesis remains incompletely characterized. Here, we document a novel role for the PDZ domain-containing scaffold protein synectin in lymphangiogenesis using genetic studies in zebrafish and tadpoles. In zebrafish, the thoracic duct arises from parachordal lymphangioblast cells, which in turn derive from secondary lymphangiogenic sprouts from the posterior cardinal vein. Morpholino knockdown of synectin in zebrafish impaired formation of the thoracic duct, due to selective defects in lymphangiogenic but not angiogenic sprouting. Synectin genetically interacted with Vegfr3 and neuropilin-2a in regulating lymphangiogenesis. Silencing of synectin in tadpoles caused lymphatic defects due to an underdevelopment and impaired migration of Prox-1+ lymphatic endothelial cells. Molecular analysis further revealed that synectin regulated Sox18-induced expression of Prox-1 and vascular endothelial growth factor C–induced migration of lymphatic endothelial cells in vitro. These findings reveal a novel role for synectin in lymphatic development.


2002 ◽  
Vol 282 (2) ◽  
pp. C395-C402 ◽  
Author(s):  
Christy-Lynn M. Cooke ◽  
Sandra T. Davidge

Peroxynitrite, a marker of oxidative stress, is elevated in conditions associated with vascular endothelial cell dysfunction, such as atherosclerosis, preeclampsia, and diabetes. However, the effects of peroxynitrite on endothelial cell function are not clear. The endothelium-derived enzymes nitric oxide synthase (NOS) and prostaglandin H synthase (PGHS) mediate vascular reactivity and contain oxidant-sensitive isoforms (iNOS and PGHS-2) that can be induced by nuclear factor (NF)-κB activation. We investigated the effect(s) of peroxynitrite on NOS and PGHS pathways in endothelial cells. We hypothesized that peroxynitrite will increase levels of iNOS and PGHS-2 through activation of NF-κB. Western immunoblots of endothelial cells show that 3-morpholinosydnonimine (SIN-1; 0.5 mM), a peroxynitrite donor, increased iNOS protein mass, which can be inhibited by pyrroline dithiocarbamate (an NF-κB inhibitor) (167 ± 24.2 vs. 78 ± 19%, P < 0.05, n = 6). SIN-1 treatment also significantly increased NF-κB translocation into endothelial cell nuclei (135 ± 10%, P < 0.05). Endothelial NOS, PGHS-1, and PGHS-2 protein levels were not altered by SIN-1. However, prostacyclin synthase protein mass, but not mRNA, was significantly reduced in SIN-1-treated endothelial cells (78 ± 8.9%, P < 0.05). Our results illustrate novel mechanisms through which peroxynitrite may modulate vascular endothelial function.


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 ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 845-845
Author(s):  
Tatiana Byzova ◽  
Juhua Chen ◽  
Payaningal R. Somanath

Abstract The major mechanism to adapt to ischemic conditions is the development of neovascularization, i.e. angiogenesis, a process driven by members of VEGF family of growth factors. Phosphoinositide 3-kinase/Akt pathway is a critical component of the signaling network that regulates endothelial cell function related to angiogenesis. VEGF treatment of endothelial cells results in rapid phosphorylation of Akt. Our studies demonstrated that Akt kinase activity is necessary for VEGF-induced and integrin-mediated endothelial cell adhesion and migration. Moreover, cell transfection with a constitutive active form of Akt (myr-Akt) leads to increased function of integrin receptors. Using Akt-1 null mice we found that Akt-1 controls VEGF-induced and integrin-dependent endothelial cell responses in vitro. Impaired endothelial cell migration and adhesion to extracellular matrix and a reduced rate of cell proliferation were observed in Akt-1 (−/−) endothelial cells compared to WT. There are three Akt isoforms with different tissue distribution, however, it appears that Akt-1 is a predominant isoform in skin and in skin microvasculature. This observation prompted us to perform series of in vivo experiments designed to assess the angiogenic response in skin in the absence of Akt-1. Angiogenesis assay using matrigel plugs revealed that the weight and hemoglobin content of matrigel plugs is about two fold higher in Akt (−/−) mice compared to WT mice. Tumor angiogenesis also appears to be enhanced in Akt(−/−) mice, resulting in the significantly lower degree of tumor necrosis. Blood vessels in Akt (−/−) mice appear to be smaller in diameter and have reduced laminin content. Our analysis revealed significant changes in blood vessel wall matrix composition of Akt (−/−) mice as compared to WT animals. These changes resulted in increased vascular permeability in skin of Akt (−/−) mice. Akt-1 is known to target multiple cellular processes including adhesive properties, cell survival, transcription and translation. It appears that the phenotype of Akt-1 (−/−) mice depends on the equilibrium between pro-angiogenic and anti-angiogenic roles of Akt-1 and reveals a central role for Akt-1 in the regulation of matrix production and maturation of blood vessels.


2007 ◽  
Vol 25 (18_suppl) ◽  
pp. 15648-15648
Author(s):  
G. Bartsch ◽  
K. Eggert ◽  
S. Loges ◽  
W. Fiedler ◽  
E. Laack ◽  
...  

15648 Background: Combinations of cytotoxic drugs lead to increased activity and minimize resistance compared to single agents in tumor therapy. Similarly, antiangiogenic treatment could be improved by combinations targeting different pathways. We investigated a combination of endogenous inhibitors using endostatin (ES), soluble Neuropilin-1 (sNP-1), and thrombospondin-2 (TSP-2) in a model of renal cell carcinoma. Methods: Porcine aortic endothelial cells have been engineered for stable production of angiogenic inhibitors by lipofection and were encapsulated in sodium alginate microbeads. Proliferation of human umbilical vein endothelial cells or Renca renal carcinoma cells was examined after incubation with different microbeads. Similarly, effects of inhibitors on endothelial cell function were tested in tube formation and in vitro wound assays. Microbeads were implanted into SCID mice with subcutaneously growing tumors derived from Renca cells or in mice developing lung metastases after intravenous injection of tumor cells. Results: Factors released from microbeads inhibited endothelial cell function but had no effect on tumor cell proliferation in vitro. In vivo, subcutaneous tumor growth was inhibited similarly by each angiogenic inhibitor alone. After 30 days mean tumor weight was 1.3 g in controls and 0.17, 0.18, 0.18g in ES, sNP-1, and TSP-2 treated mice, respectively. Tumor weight in mice treated with all three inhibitors was further reduced to 0.03g. Histological analyses confirmed antiangiogenic activity by inhibition of microvessel density in treated tumors. In a metastastic model treatment with angiogenic inhibitors induced a significant reduction in size and number of lung metastases with additive effects when factors were used in combination. Conclusions: We conclude that combination therapy targeting multiple angiogenic pathways has synergistic activity and could help to avoid resistance to single inhibitors in tumor treatment. No significant financial relationships to disclose.


Blood ◽  
2006 ◽  
Vol 107 (5) ◽  
pp. 1896-1902 ◽  
Author(s):  
Debora Faraone ◽  
Maria S. Aguzzi ◽  
Gianluca Ragone ◽  
Katia Russo ◽  
Maurizio C. Capogrossi ◽  
...  

Previous evidence has shown that platelet-derived growth factor-BB (PDGF-BB) and fibroblast growth factor-2 (FGF-2) directly interact with high affinity, leading to potent reciprocal inhibitory effects on bovine endothelial cells and rat vascular smooth muscle cells. In this study, we report that PDGF-BB inhibits a series of FGF-2–induced events, such as proliferation of human umbilical vein endothelial cells (HUVECs), FGF-2 cellular internalization, phosphorylation of intracellular signaling factors including p38, rac1/cdc42, MKK4, and MKK3/6, and phosphorylation of FGF-receptor 1 (FGF-R1). PDGF-receptor-α (PDGF-Rα) was found to mediate PDGF-BB inhibitory effects because its neutralization fully restored FGF-2 mitogenic activity and internalization. Additional biochemical analyses, coimmunoprecipitation experiments, and FRET analysis showed that FGF-R1 and PDGF-Rα directly interact in vitro and in vivo and that this interaction is somehow increased in the presence of the corresponding ligands FGF-2 and PDGF-BB. These results suggest that FGF-R1/PDGF-Rα heterodimerization may represent a novel endogenous mechanism to modulate the action of these receptors and their ligands and to control endothelial cell function.


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