Activation of endothelial nitric oxide synthase is dependent on its interaction with globular actin in human umbilical vein endothelial cells

Endothelial nitric oxide synthase (eNOS) has been reported to associate with globular actin, and this association increases eNOS activity. Adenosine, histamine, salbutamol and thrombin cause activation of eNOS through widely different mechanisms. Whether these eNOS agonists can regulate eNOS activity through affecting its association with actin is unknown. As previously reported, we confirmed in cultured human umbilical vein endothelial cells (HUVEC) that histamine and thrombin increased intracellular Ca²⁺ whereas adenosine and salbutamol did not, and that these four agonists caused different effects on actin filament structure. Nevertheless, despite their divergent effects on intracellular Ca²⁺ and on actin filament structure, we found by immunoprecipitation that adenosine, histamine, salbutamol and thrombin all caused an increase in association between eNOS and globular actin. This increase of association was inhibited by pre-treatment with phalloidin, an actin filament stabilizer. All of these agonists also increased phosphorylation of eNOS on serine residue 1177, eNOS activity, and cyclic guanosine-3′, 5′-monophosphate, and these increases were all attenuated by phalloidin. Agonist-induced phosphorylation of eNOS on serine 1177 was attenuated by Akt inhibition, whereas association of eNOS with actin was not. We also found, in HEK-293 cells transfected with the eNOS mutants eNOS-S1177A or eNOS-S1177D, that the association between eNOS and globular actin was decreased as compared to cells transfected with wild-type eNOS. We conclude that association of globular actin with eNOS plays an essential and necessary role in agonist-induced eNOS activation, through enabling its phosphorylation by Akt at serine residue 1177.     

Dose-dependent activation of Ca2+-activated K+ channels by ethanol contributes to improved endothelial cell functions

BACKGROUND: Regular moderate alcohol (EtOH) intake seems to protect against both coronary artery disease and ischemic stroke, whereas the risk increases with heavy EtOH consumption. Effects of EtOH on endothelial cell function may be relevant to these disparate effects. Potassium channels play an important role in the regulation of endothelial cell functions. Therefore, we investigated whether Ca-activated K channels (BKCa) are modulated by EtOH. Furthermore, we examined whether EtOH-induced changes of endothelial nitric oxide (NO) formation and cell proliferation are due to BKCa activation. METHODS: The patch-clamp technique was used to investigate BKCa activity in cultured human umbilical vein endothelial cells (HUVEC). NO formation was analyzed by using the fluorescence dye 4,5-diaminofluorescein. Endothelial proliferation was examined by using cell counts and measuring [H]thymidine incorporation. RESULTS: EtOH dose-dependently (10-150 mmol/liter) modulated BKCa-activity, with the highest increase of open-state probability at a concentration of 50 mmol/liter (n = 13; p < 0.05). Inside-out recordings revealed that this effect was due to direct BKCa activation, whereas open-state probability was not changed in cell-attached recordings after pertussis toxin preincubation. EtOH (10 and 50 mmol/liter) caused a significant increase of NO levels, which was blocked by the highly selective BKCa inhibitor iberiotoxin (100 nmol/l; n = 30; p < 0.05). Higher concentrations of EtOH (100 and 150 mmol/liter) significantly reduced NO synthesis (n = 30; p < 0.05). Both methods revealed a significant increase of HUVEC proliferation, which was inhibited by iberiotoxin (n = 30; p < 0.05). At a concentration of 150 mmol/liter, EtOH caused a significant reduction of endothelial proliferation. CONCLUSIONS: EtOH directly activates BKCa in HUVEC, leading to an increase of endothelial proliferation and production of NO. These results indicate a possible beneficial effect of low-dose EtOH on endothelial function, whereas higher concentrations must be considered as harmful.     

Cell-derived microparticles contain caspase 3 in vitro and in vivo.

BACKGROUND: Microparticles (MP) from endothelial cells (endothelial microparticles; EMP) circulate in disease states, but the processes such as apoptosis or cell activation underlying their release are unclear. OBJECTIVES: We investigated whether adherent (viable) or detached (apoptotic) endothelial cells are the possible source of EMP in vitro, i.e. under control and interleukin (IL)-1alpha activation conditions, and in vivo. METHODS: Adherent and detached endothelial cells, and EMP, were isolated from human umbilical vein endothelial cell cultures (n = 6), treated without or with IL-1alpha (5 ng mL(-1); 24 h). Cell fractions were analyzed by flow cytometry for annexin V binding, propidium iodide (PI) and caspase 3 staining (n = 3). Caspase 3 in EMP was studied using Western blot (n = 6) and flow cytometry (n = 6). Plasma from healthy subjects and systemic lupus erythematosus patients (both n = 3) were analyzed for caspase 3-containing (E)MP. RESULTS: Detached but not adherent cells double-stained for annexin V and PI, confirming the apoptotic conditions of the detached cells and the viable nature of the adherent cells. Caspase 3 was solely present in the detached cells and procaspase 3 in the adherent cells. Caspase 3 was present in EMP from both control and IL-1alpha-treated cultures. Counts of EMP and detached cells, but not adherent cells, highly correlated (r = 0.959, P < 0.0001). In vivo circulating MP from nucleated (endothelial cells, monocytes) and anucleated cells (platelets, erythrocytes) contained caspase 3. CONCLUSIONS: EMP contain caspase 3 and may be mainly derived from detached (apoptotic) endothelial cells in vitro. The presence of caspase 3 in MP from anucleated cell types, however, suggests that its presence may not necessarily be related to apoptosis in vivo but may be associated with caspase 3 activation unrelated to apoptosis.     

Biological activity of bevacizumab,a humanized anti-VEGF antibody <Emphasis Type="Italic">in vitro</Emphasis>

Bevacizumab (Avastin, Genentech) is a humanized monoclonal antibody targeting vascular endothelial growth factor (VEGF), a critical angiogenic factor involved in both physiological and pathological conditions. It has been recently approved by the US FDA as a first-line therapy for widespread metastatic colorectal cancer. This report is a detailed biological characterization of bevacizumab in a variety of in vitro models. It is shown that bevacizumab potently neutralizes VEGF and blocks its signal transduction through both the VEGFR-1 and VEGFR-2 receptors, as demonstrated by the inhibition of VEGF-induced cell proliferation, survival, permeability, nitric oxide production, as well as migration and tissue factor production. Although bevacizumab retains the ability to bind to human Fc receptors and complement protein C1q, it does not demonstrate cell or complement-mediated cytotoxicity in either VEGF producing or targeting cells. Thus the mechanism of anti-tumor activity of bevacizumab is most likely due to its anti-angiogenesis effect through binding and neutralization of secreted VEGF.     

Elucidation of the mechanisms underlying the angiogenic effects of ginsenoside Rg1 in vivo and in vitro

The major active constituents of ginseng are ginsenosides, and Rg₁ is a predominant compound of the total extract. Recent studies have demonstrated that Rg₁ can promote angiogenesis in vivo and in vitro. In this study, we used a DNA microarray technology to elucidate the mechanisms of action of Rg₁. We report that Rg₁ induces the proliferation of HUVECs, monitored using [³H]-thymidine incorporation and Trypan blue exclusion assays. Furthermore, Rg₁ (150–600 nM) also showed an enhanced tube forming inducing effect on the HUVEC. Rg₁ was also demonstrated to promote angiogenesis in an in vivo Matrigel plug assay, and increase endothelial sprouting in the ex vivo rat aorta ring assay. Differential gene expression profile of HUVEC following treatment with Rg₁ revealed the expression of genes related to cell adhesion, migration and cytoskeleton, including RhoA, RhoB, IQGAP1, CALM2, Vav2 and LAMA4. Our results suggest that Rg₁ can promote angiogenesis in multiple models, and this effect is partly due to the modulation of genes that are involved in the cytoskeletal dynamics, cell–cell adhesion and migration. Electronic Supplementary Material An erratum to this article can be found at     

柚皮素对ARPE-19和HUVEC细胞的抗氧化作用

目的：研究柚皮素对人视网膜色素上皮细胞（ARPE-19）和人脐静脉内皮细胞（HUVEC）的抗氧化作用。 方法：采用MTT的方法检测ARPE-19和HUVEC细胞的生存率及增殖率。 结果：3，10mg／L柚皮素能显著增加ARPE-19细胞的增殖率达10．8％和11．4％。10mg／L柚皮素能提高ARPE-19细胞在缺氧，0．3mmol／LNaN，及200μmol／L，H2O2条件下的生存率分别为55．2％，69．2％及50．3％。1mg／L柚皮素能提高ARPE-19细胞在50μmol／L t-BHP和30mg／LNaIO3条件下的生存率达20．2％和30．4％。30mg／L柚皮素能够促进ARPE-19细胞在50μmol／L t-BHP条件下的增殖率达32．2％，而1mg／L柚皮素可以提高30，100，300mg／LNaIO3处理的ARPE-19细胞的增殖率达30．3％，10．3％及18．5％。3，10及30mg／L柚皮素抑制HUVEC的增殖率分别为23．9％，70．4％及77．9％。1，3mg／L柚皮素能提高HUVEC细胞在缺氧条件下的生存率达10．7％和13．1％，以及提高在300mg／LNaIO3条件下的生存率达41．2％和37．7％。3mg／L柚皮素能提高HUVEC细胞在200，400μmol／L H2O2条件下的生存率达20．1％和21．5％． 结论：柚皮素能够促进ARPE-19细胞的增殖率，抑制HU-VEC生长，同时对这两种细胞均有抗氧化作用。因此，柚臾素是治疗老年黄斑变性的很有前景的候选药物。     

MK2 plays an important role for the increased vascular permeability that follows thermal injury

We previously reported Rho kinase is involved in vessel hyper-permeability caused by burns. Here we further explore the Rho kinase downstream signaling, it is found that its specific inhibitor Y27632 significantly diminishes the activation of JNK and p38 MAPKs but not ERK that induced by serum from burned rats (burn-serum). JNK activation was found involved in the expression of HUVEC adhesion molecules following thermal injury, although not in the process of stress fiber formation. Inhibition of various MAPKs by specific inhibitors showed that SB203580 (inhibitor of p38), but neither SP600125 (inhibitor of JNK) nor PD98059 (inhibitor of ERK), abolish activation of the p38 downstream kinase MK2. Demonstration of stress fibers by fluorescent-labeled phalloidin showed that inhibition of MK2, either by its specific inhibitor or by dominant negative adeno-viral-carried constructs, significantly reduced burn-serum-induced HUVEC stress-fiber formation, while inhibition of another downstream p38 MAPK kinase, PRAK, had no such effects. Transfection of dominant negative adeno-viral MK2 (Ad-MK2(A)) significantly inhibited thermal injury-induced blood vessel hyper-permeability in rats and, moreover, prolonged the survival of burned rats beyond 72 h following thermal injury. One of the mechanisms behind these phenomena is that Ad-MK2(A) causes a significant depression of burn-serum-induced HSP27-phosphorylation, while the adeno-viral transported dominant negative PRAK (Ad-PRAK(A)) does not block. Although the effect of blockade of MK2 through its adeno-viral approach requires further study and investigation of alternatives to know for sure, we may have found a new pathway behind thermal-injury-induced blood vessel hyper-permeability, namely: Rho kinase > p38 > MK2 > HSP27.     

基因-病毒治疗系统AdHA对血管内皮细胞的抑制作用

目的：研究基因－病毒治疗系统AdHA对血管内皮细胞增殖的抑制作用，意在为卵巢癌抗血管生成治疗提供实验依据。方法：采用直接感染台盼蓝染色排除法、MTF实验检测血管抑素K1-5对血管内皮细胞增殖的抑制作用。结果：直接感染台盼蓝染色排除法及MTT法检测表明，携带血管抑素K1-5基因的腺病毒能显著抑制血管内皮细胞增生，并对其具有杀伤力。结论：血管抑素K1—5能明显抑制血管内皮细胞增殖，为进一步行体内实验，研究其对血管形成的抑制作用及卵巢癌抗血管生成基因治疗奠定了基础。     

Calycosin protects HUVECs from advanced glycation end products-induced macrophage infiltration

Ethnopharmacological relevance

Astragali radix is a traditional Chinese medicine that has long been used for treatment of diabetes and diabetes-associated disease, but its active component and mechanism on the disease is not well defined.

Aim of the study

Infiltration of leukocytes within the glomeruli and vasculature is one of the early and characteristic features of diabetic nephropathy. Advanced glycation end products (AGEs) play pivotal role in the progression of diabetic-associated diseases. The present study was designed to explore the therapeutic effect of calycosin, an active component from A. radix, on AGEs-induced macrophages infiltration in HUVECs.

Materials and methods

Transwell HUVEC-macrophage co-culture system was established to evaluate macrophage migration and adhesion. Immunocytochemistry was applied to examine TGF-beta1, ICAM-1 and RAGE protein expressions; real-time PCR was carried out to determine mRNA expression of TGF-beta1, ICAM-1 and RAGE. Immunofluorescence was carried out to observe estrogen receptor-alpha, ICAM-1, RAGE expression and the phosphorylation status of ERK1/2 and NF-κB.

Results

Calycosin significantly reduced AGEs-induced macrophage migration and adhesion to HUVEC. Pre-treatment with calycosin strikingly down-regulated HUVEC TGF-beta1, ICAM-1 and RAGE expressions in both protein and mRNA levels. Furthermore, calycosin incubation significantly increased estrogen receptor expression and reversed AGEs-induced ERK1/2 and NF-κB phosphorylation and nuclear translocation in HUVEC, and this effect of calycosin could be inhibited by estrogen receptor inhibitor, ICI182780.

Conclusions

These findings suggest that calycosin can reduce AGEs-induced macrophage migration and adhesion to endothelial cells and relieve the local inflammation; furthermore, this effect was via estrogen receptor-ERK1/2-NF-κB pathway.