Effects of Ginsenosides on LPS-induced TF and PAI-1 expression in vascular endothelial cells

AIM: To study the effect of ginsenosides on lipopolysaccharide-induced expression of tissue factor (TF) and plasminogen activator inhibitor type-1 (PAI-1) in vascular endothelial cells (EC), and to investigate the mechanism of ginsenosides in the healthy protection and treatment of cardiovascular diseases. METHODS: Human umbilical vein endothelial cells (HUVEC) were cultured by trypsin digestion method. PAI-1 was measured in the conditioned medium of HUVEC by a specific enzyme-linked immunosorbent assay (ELISA), whereas TF activity was measured in the lysates of these cells by a single step clotting assay. Specific mRNA expressions were determined by Northern blotting. RESULTS: Treatment of HUVEC with LPS resulted in a significant increase in PAI-1 antigen and TF activity. Ginsenosides inhibited this LPS-induced upregulation of PAI-1 protein and TF activity in HUVEC. These effects were also confirmed on the level of specific PAI-1 and TF mRNA expression by Northern blotting. CONCLUSION: Ginsenosides counteract endothelial cell activation by inhibition LPS-induced PAI-1 and TF expression in these cells. This ability of ginsenosides might explain its efficacy in the healthy protection and the treatment of cardiovascular diseases.     

Effects of miR-30c on viability and migratory ability of HUVECs by targeting PAI-1

AIM: To investigate the effect of microRNA (miR)-30c on the viability and migratory ability of human umbilical vein endothelial cells (HUVECs) by targeting plasminogen activator inhibitor-1 (PAI-1).METHODS: The HUVECs were transfected with miR-30c mimic and inhibitor or negative control (NC), and then the expression levels of miR-30c, PAI-1 mRNA and protein were detected by RT-qPCR and Western blot. The viability and migratory ability of HUVECs were measured by CCK-8 assay and wound healing test. After bioinformatic analysis, the assessment of miR-30c binding to PAI-1 3'-UTR was carried out using a luciferase reporter gene assay. RESULTS: miR-30c directly down-regulated PAI-1 levels by binding to the 3' UTR seed sequence of PAI-1 mRNA. Furthermore, transfection of a miR-30c mimic down-regulated the expression of PAI-1 at mRNA and protein levels, leading to enhanced migratory ability and viability of the HUVECs. However, transfection of a miR-30c inhibitor up-regulated the expression of PAI-1 at mRNA and protein le-vels, leading to decreased migratory ability and viability. CONCLUSION: Regulation of miR-30c level changes the migratory ability and viability of HUVECs by affecting the PAI-1 expression, indicating the involvement of miR-30c in modulating endothelial function.     

Role of SIRT1/eNOS/NO signaling pathway in protective effect of ginsenoside Rb1 against replicative senescence of endothelial cells

AIM: To explore the effect of ginsenoside Rb1 on replicative senescence of endothelial cells and the role of SIRT1/eNOS/NO signaling pathway in this process. METHODS: The replicative senescence model of primary human umbilical vein endothelial cells (HUVECs) was established. The morphological change of the cells, the proportion of senescence-associated β-galactosidase (SA-β-Gal) positive cells and the plasminogen activator inhibitor 1 (PAI-1) expression were detected to assess the senescence model. The expression of eNOS and PAI-1 at mRNA and protein levels in the aging cells was determined by real-time PCR and Western blot before and after silencing of SIRT1 was performed. The NO concentration in the cell culture supernatant was measured by nitrate reductase assay. RESULTS: HUVECs with cumulative population-doubling level (CPDL) at 16 were chosen as the replicative senescence model in this research. Ginsenoside Rb1 at 80 μmol/L significantly reduced the expression of PAI-1 at mRNA and protein levels. Furthermore, ginsenoside Rb1 increased the expression of SIRT1 and eNOS at mRNA and protein levels, and increased the NO content. SIRT1 silencing inhibited the expression of eNOS at mRNA and protein levels and reduced NO generation, leading to an increase in the expression of PAI-1 at mRNA and protein levels. Upon intervention of ginsenoside Rb1, the eNOS and PAI-1 expression and the level of NO were not reversed. CONCLUSION: Ginsenoside Rb1 modulates SIRT1/eNOS/NO signaling pathway to prevent the replicative senescence of HUVECs.     

Influence of different flow pattern on VCAM-1, NF-κB expression in vascular endothelial cells

AIM:The objective of this study was to examine the influence of different flow pattern, particularly low shear stress flow regimens, on VCAM-1 and NF-κB in vascular endothelial cells. METHODS:HUVEC covered sheets were placed within rectangular parallel plate flow chambers. Cells were subjected to 4, 18 h of either laminar or oscillatory shear stress. The expression of VCAM-1 and NF-κB activity were analyzed by immunohistochemistry. VCAM-1 mRNA was also detected using in situ hybridization. RESULTS:VCAM-1 mRNA and VCAM-1 expression were not upregulated by laminar shear stress. However, oscillatory shear stress significantly upregulated VCAM-1 mRNA and VCAM-1 expression. Translocation of NF-κB P65 was remarkably increased.CONCLUSION:In same low shear stress, the different expression of VCAM-1 mRNA and VCAM-1 were induced by HUVEC exposed to laminar or oscillatory flow patterns.     

Effect of P53 binding site on regulation of human NOD8 gene

AIM: To investigated the characterization and biological function of P53 binding element in the regulation of NOD8 gene. METHODS: Using the method of bioinformatics, we found a completely preserved P53 binding site in NOD8 core promoter both in humans and chimpanzees. NOD8 gene was amplified by PCR from human cDNA and correctly connected into the vector p NOD8 (760 bp)-EGFP-C2/ mp NOD8 (750 bp)-EGFP-C2. The constructed plasmids p NOD8 (760 bp)-EGFP- NOD8 and mp NOD8 (750 bp)-EGFP- NOD8 were transiently transfected into the cell line HEK293 by JetPei^TM and treated with pifithrin alpha (PFT-α,an inhibitor of P53) at different concentrations for 24 h. The mRNA and protein expression levels of NOD8 were detected by RT-PCR and Western blotting. In addition, chromatin immunoprecipitation (ChIP) assay was performed to determine the binding of P53 to the NOD8 promoter after recombinant plasmid p NOD8 (760 bp)-EGFP was transfected into HEK293 cells. RESULTS: The plasmids p NOD8 (760 bp) -EGFP- NOD8 and mp NOD8 (750 bp)-EGFP- NOD8 were successfully constructed and conformed by restriction digestion and sequence analysis. The results of ChIP confirmed that P53 bound to the promoter of NOD8 . The mRNA expression of NOD8 in the cells transfected with p NOD8 (760 bp)-EGFP- NOD8 was stronger than that in the cells transfected with control vector pEGFP-C2 (P<0.05). Furthermore, the mRNA expression of NOD8 was reduced in HEK293 cells transfectnt with the mutant plasmid mp NOD8 (750 bp)-EGFP- NOD8 compared with the cells transfected with p NOD8 (760 bp)-EGFP- NOD8 . Meanwhile, PFT-α inhibited the mRNA expression of NOD8 in the cells transfected with p NOD8 (760 bp)-EGFP- NOD8 in a concentration-dependent manner, and PFT-α at concentration of 90 μmol/L was the most effective in inhibiting NOD8 mRNA expression (P<0.01). As expected, the protein expression of NOD8 in pNOD8 (760 bp)-EGFP- NOD8 group significantly increased compared with that in pNOD8 -C2 group, the protein expression of NOD8 in mp NOD8 (750 bp)-EGFP- NOD8 group or pNOD8 (760 bp)-EGFP- NOD8 + PFT-α group was dramatically decreased compared with that in p NOD8 (760 bp) -EGFP- NOD8 group. CONCLUSION: The results suggest that the P53 binding site is critical for the regulation of NOD8 gene and there is positive feedback regulation between P53 binding site and NOD8 , which may maintain efficient balance between defense and self-inflicted injury in response to the invasion of pathogen.     

Effect of lysophosphatidic acid on expression of integrin β6 in epithelial cells

AIM: To investigate the effect of lysophosphatidic acid (LPA) on the expression of integrin β₆ (ITGB6) for determining the role of transforming growth factor β (TGF-β) activation induced by LPA in this process. METHODS: Normal human bronchial epithelial (NHBE) cells were primarily cultured in 6 well plate and stimulated with LPA. The mRNA expression of ITGB6 and the level of cell surface ITGB6 protein were detected by RT-PCR and flow cytometry,respectively. The activity of active TGF-β induced by LPA was measured by the method of transformed mink lung epithelial cells (TMLC) transfected with TGF-β responsive plasminogen activator inhibitor 1(PAI-1) promoter fused with firefly luciferase reporter gene. RESULTS: After stimulated with LPA at concentration of 10 μmol/L for 2 h, the mRNA expression of ITGB6 in epithelial cells was significantly increased in a time-dependent manner. The results of flow cytometry showed that the protein level of ITGB6 on cell surface was obviously increased after treated with LPA at concentration of 10 μmol/L for 4 h. The active TGF-β induced by LPA in epithelial cells was blocked by an α_Vβ₆ blocking antibody. However, α_Vβ₆ blocking antibody failed to inhibit the mRNA expression of ITGB6 induced by LPA. CONCLUSION: LPA induces the mRNA and cell surface protein of ITGB6 in epithelial cells. The up-regulated ITGB6 expression by LPA is independent on LPA-induced TGF-β activation.     

Response of CREG1 promoter to serum starvation in human vascular cells

AIM: In order to explore the regulatory mechanisms of the human cellular repressor of E1A-stimulated genes (hCREG1) in vascular smooth muscle cells (VSMCs)-HITASY and in human umbilical vein endothelial cells (HUVECs), we clone and construct hCREG1 promoter vector to detect its expression in different vascular cells. METHODS: With the results of biological information, the fragments including -3 677 bp, -2 310 bp and -945 bp upstream sequences of hCREG1 were amplified respectively using human genomic DNA template by PCR. The products were inserted into pMD18-T vector, and then were subcloned into pEGFP-1 report vector to obtain the pEGFP-hCREG1-promoter vectors. The pEGFP-hCREG1-P3677, pEGFP-hCREG1-P2310 and pEGFP-hCREG1-P945 vectors were transfected into HITASY cells and HUVECs transiently and the expression of green fluorescent protein (GFP) was detected respectively by Western blotting and fluorescent microscope. RESULTS: It was confirmed that all three PCR fragments inserted into vectors were corrected by sequencing analysis. However, the expression of GFP was different significantly in both types of vascular cells. The expression of GFP in HUVECs was higher than that in HITASY cells. Meanwhile, the expression of GFP in HITASY cells with 0.5% FBS was increased obviously compared to that in HITASY cells with 10% FBS. CONCLUSION: The reporter vectors of hCREG1 promoter are constructed successfully in which the core promoter region might be located in -945 bp-0 bp of 5′ upstream sequences. This study will provide an experimental basis for exploring the regulation of hCREG1 expression.     

Effects of testosterone on the fibrinolysis activity of HUVEC and its mechanism

AIM: To investigate the effect of testosterone with varied concentrations on the fibrinolysis activity of HUVEC and its mechanism.METHODS: Human umbilical vein endothelial cells (HUVEC) were cultured as recommended. After confluence, the cultures were treated with testosterone(3 ×10-10, 3×10-9, 3×10-8,3×10-6, 3×10-5 mol/L) , and the control confluent cells were cultured in the same medium without steroid. MTT experiment was repeated for 72 hours to investigate each groups’ cell proliferation. The tPA and PAI-1 antigen levels were assayed with ELISA Kits. Then with HUVEC incubated in androgen receptor antagonist (flutamide) 3 hours previously, the experiment was repeated. RESULTS: Testosterone at physiologic or lower concentrations (3 ×10-10 to 3×10-8 mol/L ) stimulated the secretion of tPA by HUVEC (P＜0.01). However, tPA levels markedly reduced at larger doses (3 ×10-6 to 3×10-5 mol/L). On the other hand， PAI-1 antigen levels decreased significantly at the testosterone concentrations ranging from 3 ×10-10 to 3×10-5 mol/L (P＜0.05). Flutamide attenuated the testosterone’s effects (P＜0.05). CONCLUSIONS: The results indicated that testosterone at physiologically relevant concentrations decreased PAI-1, while increased tPA levels via the androgen receptor, which suggested that testosterone may have beneficial effects on preventing thrombotic diseases.