Overexpression of CREG attenuates atherosclerotic endothelium apoptosis via VEGF/PI3K/AKT pathway

Exploring the Mechanism of Si-miao-yong-an Decoction in the Treatment of Coronary Heart Disease based on Network Pharmacology and Experimental Verification

BACKGROUND

To investigate the active ingredients and the mechanisms of Si-miaoyong- an Decoction (SMYA) in the treatment of coronary heart disease (CHD) by using network pharmacology, molecular docking technology, and in vitro validation.

METHODS

Through the Chinese Medicine System Pharmacology Database and Analysis Platform (TCMSP), Uniprot database, GeneCards database, and DAVID database, we explored the core compounds, core targets and signal pathways of the effective compounds of SMYA in the treatment of CHD. Molecular docking technology was applied to evaluate the interactions between active compounds and key targets. The hypoxia-reoxygenation H9C2 cell model was applied to carry out in vitro verification experiments. A total of 109 active ingredients and 242 potential targets were screened from SMYA. A total of 1491 CHD-related targets were retrieved through the Gene- Cards database and 155 overlapping CHD-related SMYA targets were obtained. PPI network topology analysis indicated that the core targets of SMYA in the treatment of CHD include interleukin- 6 (IL-6), tumor suppressor gene (TP53), tumor necrosis factor (TNF), vascular endothelial growth factor A (VEGFA), phosphorylated protein kinase (AKT1) and mitogen-activated protein kinase (MAPK). KEGG enrichment analysis demonstrated that SMYA could regulate Pathways in cancer, phosphatidylinositol 3 kinase/protein kinase B (PI3K/Akt) signaling pathway, hypoxiainducible factor-1(HIF-1) signaling pathway, VEGF signaling pathway, etc. Results: Molecular docking showed that quercetin had a significant binding activity with VEGFA and AKT1. In vitro studies verified that quercetin, the major effective component of SMYA, has a protective effect on the cell injury model of cardiomyocytes, partially by up-regulating expressions of phosphorylated AKT1 and VEGFA.

CONCLUSION

SMYA has multiple components and treats CHD by acting on multiple targets. Quercetin is one of its key ingredients and may protect against CHD by regulating AKT/VEGFA pathway.

Interplay between PI3K/AKT pathway and heart disorders

The PI3K/AKT signaling has crucial role in the regulation of numerous physiological functions through activation of downstream effectors and modulation of cell cycle transition, growth and proliferation. This pathway participates in the pathogenesis of several human disorders such as heart diseases through regulation of size and survival of cardiomyocytes, angiogenic processes as well as inflammatory responses. Moreover, PI3K/AKT pathway participates in the process of myocardial injury induced by a number of substances such as H₂O₂, Mercury, lipopolysaccharides, adriamycin, doxorubicin and epirubicin. In this review, we describe the contribution of this pathway in the pathoetiology of myocardial ischemia/reperfusion injury and myocardial infarction, heart failure, cardiac hypertrophy, cardiomyopathy and toxins-induced cardiac injury.

CREG mitigates neonatal HIE injury through survival promotion and apoptosis inhibition in hippocampal neurons via activating AKT signaling

Neonatal hypoxic ischemic encephalopathy (Neonatal HIE) is a common but serious disease caused by perinatal asphyxia injury in newborns. Elevated neuronal apoptosis plays an important role in the injury process post hypoxia ischemia of the brain, which accurate mechanism is still worthy to be studied. Cellular repressor of E1A-stimulated genes (CREG) possesses the protective effect in ischemia-reperfusion in multiple organs, including livers and hearts. The main purpose of this work was to investigate whether CREG was involved in alleviating neonatal HIE and explore the possible mechanisms. We found that CREG expression was down-regulated in the hippocampus of neonatal HIE rats as well as oxygen-glucose deprivation/reperfusion (OGD/R)-treated hippocampal neurons. Besides, CREG overexpression promoted survival while inhibited apoptosis in OGD/R-induced hippocampal neurons accompanied by AKT signaling activation, which could be reversed by CREG silence. In addition, the protective effects of CREG overexpression could be antagonized by AKT deactivation, indicating the function of CREG was attributed by regulating AKT pathway. Collectedly, we demonstrated that CREG protected hippocampal neurons from hypoxic ischemia-induced injury through regulating survival and apoptosis via activating AKT signaling pathway. This article is protected by copyright. All rights reserved.

TCM Regulates PI3K/Akt Signal Pathway to Intervene Atherosclerotic Cardiovascular Disease

Vascular endothelial injury is the initial stage of atherosclerosis (AS). Stimulating and activating the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway can regulate the expression of vascular endothelial cytokines, thus affecting the occurrence and development of AS. In addition, the PI3K/Akt signaling pathway can regulate the polarization and survival of macrophages and the expression of inflammatory factors and platelet function, thus influencing the progression of AS. In recent years, traditional Chinese medicine (TCM) has been widely recognized for its advantages of fewer side effects, multiple pathways, and multiple targets. Also, the research of TCM regulation of AS via the PI3K/Akt signaling pathway has achieved certain results. This study aimed to analyze the characteristics of the PI3K/Akt signaling pathway and its role in the pathogenesis of AS, as well as the role of Chinese medicine in regulating the PI3K/Akt signaling pathway. The findings are expected to provide a theoretical basis for the clinical treatment and pathological mechanism research of AS.

Detection of an anti-angina therapeutic module in the effective population treated by a multi-target drug Danhong injection: a randomized trial

It’s a challenge for detecting the therapeutic targets of a polypharmacological drug from variations in the responsed networks in the differentiated populations with complex diseases, as stable coronary heart disease. Here, in an adaptive, 31-center, randomized, double-blind trial involving 920 patients with moderate symptomatic stable angina treated by 14-day Danhong injection(DHI), a kind of polypharmacological drug with high quality control, or placebo (0.9% saline), with 76-day following-up, we firstly confirmed that DHI could increase the proportion of patients with clinically significant changes on angina-frequency assessed by Seattle Angina Questionnaire (ΔSAQ-AF ≥ 20) (12.78% at Day 30, 95% confidence interval [CI] 5.86–19.71%, P = 0.0003, 13.82% at Day 60, 95% CI 6.82–20.82%, P = 0.0001 and 8.95% at Day 90, 95% CI 2.06–15.85%, P = 0.01). We also found that there were no significant differences in new-onset major vascular events (P = 0.8502) and serious adverse events (P = 0.9105) between DHI and placebo. After performing the RNA sequencing in 62 selected patients, we developed a systemic modular approach to identify differentially expressed modules (DEMs) of DHI with the Z_summary value less than 0 compared with the control group, calculated by weighted gene co-expression network analysis (WGCNA), and sketched out the basic framework on a modular map with 25 functional modules targeted by DHI. Furthermore, the effective therapeutic module (ETM), defined as the highest correlation value with the phenotype alteration (ΔSAQ-AF, the change in SAQ-AF at Day 30 from baseline) calculated by WGCNA, was identified in the population with the best effect (ΔSAQ-AF ≥ 40), which is related to anticoagulation and regulation of cholesterol metabolism. We assessed the modular flexibility of this ETM using the global topological D value based on Euclidean distance, which is correlated with phenotype alteration (r²: 0.8204, P = 0.019) by linear regression. Our study identified the anti-angina therapeutic module in the effective population treated by the multi-target drug. Modular methods facilitate the discovery of network pharmacological mechanisms and the advancement of precision medicine. (ClinicalTrials.gov identifier: NCT01681316).

Fruquintinib inhibits VEGF/VEGFR2 axis of choroidal endothelial cells and M1-type macrophages to protect against mouse laser-induced choroidal neovascularization

Wet age-related macular degeneration, which is characterized by choroidal neovascularization (CNV) and induces obvious vision loss. Vascular endothelial growth factor (VEGF) family member VEGF-A (also named as VEGF) and its receptor VEGFR2 contribute to the pathogenesis of CNV. Choroidal endothelial cells (CECs) secret C–C motif chemokine ligand 2 (CCL2), which attracts macrophages to CNV lesion and promotes macrophage M1 polarization. Accordingly, infiltrating macrophages secret inflammatory cytokines to promote CNV. In vivo, intravitreal injection of fruquintinib (HMPL-013), an antitumor neovascularization drug, alleviated mouse CNV formation without obvious ocular toxicity. Meanwhile, HMPL-013 inhibited VEGF/VEGFR2 binding in CECs and macrophages, as well as macrophage M1 polarization. In vitro, noncontact coculture of human choroidal vascular endothelial cells (HCVECs) and macrophages under hypoxia conditions was established. HMPL-013 downregulated VEGF/VEGFR2/phosphoinositide-3-kinase/protein kinase B (AKT)/nuclear factor kappa B pathway and CCL2 secretion in HCVECs, as well as VEGF/VEGFR2-induced macrophage M1 polarization under hypoxia condition. In addition, HMPL-013 inhibited HCEVC derived CCL2-induced macrophage migration and M1 polarization, along with macrophage M1 polarization-induced HCVECs proliferation, migration, and tube formation. Altogether, HMPL-013 alleviated CNV formation might via breaking detrimental cross talk between CECs and macrophages.

DNA hypermethylation: A novel mechanism of CREG gene suppression and atherosclerogenic endothelial dysfunction

OBJECTIVE

Cellular repressor of E1A-stimulated genes (CREG), a vasculoprotective molecule, is significantly downregulated in atherosclerotic vessels through unclear mechanisms. While epigenetic regulation is involved in atherosclerosis development, it is not known if the CREG gene is epigenetically regulated. The aim of this study was to assess the potential role of CREG methylation in contributing to atherosclerosis.

APPROACH AND RESULTS

Overexpression of DNA methyltransferase (DNMT)3B significantly inhibited CREG expression in human umbilical vein endothelial cells (HUVECs) and human coronary aortic endothelial cells (HCAECs).Conversely, inhibition of DNA methylation with 5-aza-2'-deoxycytidine (5-aza-dC) dose-dependently increased CREG expression. A CREG promoter analysis identified +168 to +255 bp as a key regulatory region and the CG site at +201/+202 bp as a key methylation site. The transcription factor GR-α could bind to the +201/+202 bp CG site promoting CREG transcription, a process significantly inhibited by DNMT3B overexpression. Treatment of cells with oxidized low-density lipoprotein (ox-LDL), a critical atherosclerogenic factor, significantly increased DNMT3B expression, increasing CREG promotor methylation, blocking GR-α binding, and inhibiting CREG expression. Consistently, CG sites in the CREG promoter fragment were hyper-methylated in human atherosclerotic arteries, and CREG expression was significantly reduced. A negative correlation between DNMT3B and CREG expression levels was observed in human atherosclerotic arteries. Finally, Ox-LDL-induced endothelium dysfunction was significantly attenuated by both 5-aza-dC and an anti-oxidative molecular N-acetylcysteine (NAC) administration through rescue the expression of CREG and activation of the p-eNOS/NO pathway.

CONCLUSIONS

Our study provides the first direct evidence that DNMT3B-mediated CREG gene hypermethylation is a novel mechanism that contributes to endothelial dysfunction and atherosclerosis development. Blocking CREG methylation may represent a novel therapeutic approach to treat ox-LDL-induced atherosclerosis.

Antiapoptotic role of the cellular repressor of E1A-stimulated genes (CREG) in retinal photoreceptor cells in a rat model of light-induced retinal injury

OBJECTIVE

Light injury-induced apoptosis of retinal photoreceptor cells can lead to vision loss. The mechanism underlying such injury remains unclear, and there are no effective therapies at present. The aim of this study was to examine the potential antiapoptotic role of the cellular repressor of E1A-stimulated genes (CREG) in retinal cells in a rat model of light-induced retinal damage.

METHODS

CREG proteins were injected into the vitreous space of rats in which light retinal injury was induced. An equal volume of PBS was injected into the vitreous space of a control group. Retinas were collected for H&E staining and Western blotting analysis 1, 3, and 7 days later. Inhibitors or agonist for P38, JNK, and AKT were injected into the vitreous space to verify CREG function.

RESULTS

In rats with light-induced retinal injury, the CREG treatment inhibited the expression of apoptosis-related proteins caspase-3, caspase-8, and caspase-9 and signaling proteins phosphorylated ERK (P-ERK), phosphorylated JNK (P-JNK), phosphorylated P38 (P-P38), and phosphorylated AKT (P-AKT). An inhibitor of PI3K-AKT and an agonists of P38 and JNK abrogated the inhibitory effect of CREG on caspase-3 expression.

CONCLUSION

CREG protected retinal cells against apoptosis by inhibiting P38/MAPK and JNK/MAPK signaling pathways and activating the PI3K-AKT signaling pathway.

CREG1 heterozygous mice are susceptible to high fat diet-induced obesity and insulin resistance

Cellular repressor of E1A-stimulated genes 1 (CREG1) is a small glycoprotein whose physiological function is unknown. In cell culture studies, CREG1 promotes cellular differentiation and maturation. To elucidate its physiological functions, we deleted the Creg1 gene in mice and found that loss of CREG1 leads to early embryonic death, suggesting that it is essential for early development. In the analysis of Creg1 heterozygous mice, we unexpectedly observed that they developed obesity as they get older. In this study, we further studied this phenotype by feeding wild type (WT) and Creg1 heterozygote (Creg1^+/-) mice a high fat diet (HFD) for 16 weeks. Our data showed that Creg1^+/- mice exhibited a more prominent obesity phenotype with no change in food intake compared with WT controls when challenged with HFD. Creg1 haploinsufficiency also exacerbated HFD-induced liver steatosis, dyslipidemia and insulin resistance. In addition, HFD markedly increased pro-inflammatory cytokines in plasma and epididymal adipose tissue in Creg1^+/- mice as compared with WT controls. The activation level of NF-κB, a major regulator of inflammatory response, in epididymal adipose tissue was also elevated in parallel with the cytokines in Creg1^+/- mice. These pro-inflammatory responses elicited by CREG1 reduction were confirmed in 3T3-L1-derived adipocytes with CREG1 depletion by siRNA transfection. Given that adipose tissue inflammation has been shown to play a key role in obesity-induced insulin resistance and metabolic syndrome, our results suggest that Creg1 haploinsufficiency confers increased susceptibility of adipose tissue to inflammation, leading to aggravated obesity and insulin resistance when challenged with HFD. This study uncovered a novel function of CREG1 in metabolic disorders.

Tanshinone IIA combined with adriamycin inhibited malignant biological behaviors of NSCLC A549 cell line in a synergistic way

Background

The study was designed to develop a platform to verify whether the extract of herbs combined with chemotherapy drugs play a synergistic role in anti-tumor effects, and to provide experimental evidence and theoretical reference for finding new effective sensitizers.

Methods

Inhibition of tanshinone IIA and adriamycin on the proliferation of A549, PC9 and HLF cells were assessed by CCK8 assays. The combination index (CI) was calculated with the Chou-Talalay method, based on the median-effect principle. Migration and invasion ability of A549 cells were determined by wound healing assay and transwell assay. Flow cytometry was used to detect the cell apoptosis and the distribution of cell cycles. TUNEL staining was used to detect the apoptotic cells. Immunofluorescence staining was used to detect the expression of Cleaved Caspase-3. Western blotting was used to detect the proteins expression of relative apoptotic signal pathways. CDOCKER module in DS 2.5 was used to detect the binding modes of the drugs and the proteins.

Results

Both tanshinone IIA and adriamycin could inhibit the growth of A549, PC9, and HLF cells in a dose- and time-dependent manner, while the proliferative inhibition effect of tanshinone IIA on cells was much weaker than that of adriamycin. Different from the cancer cells, HLF cells displayed a stronger sensitivity to adriamycin, and a weaker sensitivity to tanshinone IIA. When tanshinone IIA combined with adriamycin at a ratio of 20:1, they exhibited a synergistic anti-proliferation effect on A549 and PC9 cells, but not in HLF cells. Tanshinone IIA combined with adriamycin could synergistically inhibit migration, induce apoptosis and arrest cell cycle at the S and G2 phases in A549 cells. Both groups of the single drug treatment and the drug combination up-regulated the expressions of Cleaved Caspase-3 and Bax, but down-regulated the expressions of VEGF, VEGFR2, p-PI3K, p-Akt, Bcl-2, and Caspase-3 protein. Compared with the single drug treatment groups, the drug combination groups were more statistically significant. The molecular docking algorithms indicated that tanshinone IIA could be docked into the active sites of all the tested proteins with H-bond and aromatic interactions, compared with that of adriamycin.

Conclusions

Tanshinone IIA can be developed as a novel agent in the postoperative adjuvant therapy combined with other anti-tumor agents, and improve the sensibility of chemotherapeutics for non-small cell lung cancer with fewer side effects. In addition, this experiment can not only provide a reference for the development of more effective anti-tumor medicine ingredients, but also build a platform for evaluating the anti-tumor effects of Chinese herbal medicines in combination with chemotherapy drugs.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2921-x) contains supplementary material, which is available to authorized users.

Protective effect of oleanolic acid on oxidized-low density lipoprotein induced endothelial cell apoptosis

Oleanolic acid (3β-hydroxyolean-12-en-28-oic acid, OA) is a naturally-occurring triterpenoid with various promising pharmacological properties. The present study was conducted to determine the protective effects of OA against oxidized low-density lipoprotein (ox-LDL) induced endothelial cell apoptosis and the possible underlying mechanisms. Our results showed that ox-LDL significantly decreased cell viability and induced apoptosis in human umbilical vein endothelial cells (HUVECs). OA in the co-treatment showed a protective effect against ox-LDL induced loss in cell viability and an increase in apoptosis, which was associated with the modulating effect of OA on ox-LDL induced hypoxia-inducible factor 1α(HIF-1α) expression. Moreover, our results showed that the modulating effect of OA against ox-LDL induced HIF-1α expression was obtained via inhibition of lipoprotein receptor 1 (LOX-1)/reactive oxygen species (ROS) signaling. Collectively, we suggested that the protective effect of OA against ox-LDL induced HUVEC apoptosis might, at least in part, be obtained via inhibition of the LOX-1/ROS/HIF-1α signaling pathway.

Up-Regulation of CREG Expression by the Transcription Factor GATA1 Inhibits High Glucose- and High Palmitate-Induced Apoptosis in Human Umbilical Vein Endothelial Cells

Background

Endothelial cell (EC) apoptosis plays a vital role in the pathogenesis of atherosclerosis in patients with diabetes mellitus (DM), but the underlying mechanism remains unclear. Cellular repressor of E1A-stimulated genes (CREG) is a novel gene reported to be involved in maintaining the homeostasis of ECs. Therefore, in the present study, we investigated the role of CREG in high glucose/high palmitate-induced EC apoptosis and to decipher the upstream regulatory mechanism underlying the transcriptional regulation of CREG.

Methods

The expression of CREG and the rate of apoptosis were assessed in lower-limb atherosclerotic lesions from patients with type 2 DM (T2DM). Primary human umbilical vein endothelial cells (HUVECs) were isolated and cultured in a high glucose/high palmitate medium (25 mmol/L D-glucose, 0.4 mmol/L palmitate), and the over-expression and knock-down of CREG were performed in HUVECs to determine the role of CREG in EC apoptosis. The upstream regulatory mechanism of CREG was identified using a promoter-binding transcription-factor profiling array, chromatin immunoprecipitation (ChIP) assay and a mutation analysis.

Results

Compared with normal arteries from non-diabetic patients, reduced CREG expression and increased apoptosis were found in the endothelium of atherosclerotic lesions from patients with T2DM. In vitro treatment of HUVECs with a high glucose/high palmitate medium also resulted in decreased CREG expression and increased apoptosis. Moreover, high glucose/high palmitate induced-HUVEC apoptosis was increased by the knock-down of CREG and rescued by the over-expression of CREG. We also demonstrated that GATA1 was able to bind to the promoter of the human CREG gene. A deletion mutation at -297/-292 in the CREG promoter disrupted GATA1 binding and reduced the activation of CREG transcription by approximately 83.3%. Finally, the overexpression of GATA1 abrogated the high glucose/high palmitate-induced apoptosis in HUVECs.

Conclusions

The over-expression of CREG inhibits high glucose/high palmitate-induced apoptosis in HUVECs. CREG is transcriptionally upregulated by GATA1. Thus, CREG might be a potential therapeutic target for intervention of vascular complications related to diabetes.

Wen-Xin Decoction ameliorates vascular endothelium dysfunction via the PI3K/AKT/eNOS pathway in experimental atherosclerosis in rats

Background

Nitric oxide (NO) is the most powerful vasodilator that inhibits leukocyte adhesion, platelet aggregation, and vascular smooth muscle cell proliferation. However, excessive NO can cause lipid peroxidation and direct endothelial cell damage. Therefore, investigation of the role of NO in artherosclerosis development is important. Wen-Xin Decoction (WXD) has been shown to relieve myocardial ischemia reperfusion injury and prevent leukocyte adhesion and invasion; in addition, it can accelerate angiogenesis and prevent platelet activation and aggregation. In this study, we focused on the NO pathway to further clarify the protective effects of WXD on the vascular endothelium in rat models of artherosclerosis.

Methods

Wistar rats were randomly divided into a normal group (n = 10) and a model group (n = 75). Rat models of atherosclerosis were generated by intraperitoneal vitamin D3 (3 months) injections and administration of a high-fat diet (3 months with vitamin D3 and 2 months alone). The model rats were randomly divided into five groups (n = 15 each): model (saline), atorvastatin (4.8 mg/kg/d atorvastatin), high-dose WXD (9 g/kg/d), medium-dose WXD (4.5 g/kg/d), and low-dose WXD (2.25 g/kg/d) groups. Each group received continuous drug or saline administration (suspended liquid gavage) for 30 days, following which all animals were sacrificed. The ultrastructure and histopathological changes of vascular endothelial cells and the expression of PI3K/AKT/eNOS and iNOS in the thoracic aorta tissue were analyzed.

Results

WXD increased NO levels, modulated the NO/ET-1 ratio, and promoted repair of the injured vascular endothelium in a dose-dependent manner. At a high dose, WXD regulated the NO/ET-1 ratio as effectively as atorvastatin; furthermore, it increased NO levels within the physiological range to prevent endothelial damage caused by excessive NO expression. Real-time polymerase chain reaction and Western blot analysis showed that WXD significantly upregulated the mRNA and protein expressions of PI3K, AKT, and eNOS mRNA and significantly increased AKT and eNOS phosphorylation.

Conclusions

Our results suggest that WXD protects and maintains the integrity of the vascular endothelium by activating the PI3K/AKT/eNOS pathway, decreasing iNOS expression, and promoting the release of physiological NO levels.

Glycoproteomic Approach Identifies KRAS as a Positive Regulator of CREG1 in Non-small Cell Lung Cancer Cells

Protein glycosylation plays a fundamental role in a multitude of biological processes, and the associated aberrant expression of glycoproteins in cancer has made them attractive biomarkers and therapeutic targets. In this study, we examined differentially expressed glycoproteins in cell lines derived from three different states of lung tumorigenesis: an immortalized bronchial epithelial cell (HBE) line, a non-small cell lung cancer (NSCLC) cell line harboring a Kirsten rat sarcoma viral oncogene homolog (KRAS) activation mutation and a NSCLC cell line harboring an epidermal growth factor receptor (EGFR) activation deletion. Using a Triple SILAC proteomic quantification strategy paired with hydrazide chemistry N-linked glycopeptide enrichment, we quantified 118 glycopeptides in the three cell lines derived from 82 glycoproteins. Proteomic profiling revealed 27 glycopeptides overexpressed in both NSCLC cell lines, 6 glycopeptides overexpressed only in the EGFR mutant cells and 19 glycopeptides overexpressed only in the KRAS mutant cells. Further investigation of a panel of NSCLC cell lines found that Cellular repressor of E1A-stimulated genes (CREG1) overexpression was closely correlated with KRAS mutation status in NSCLC cells and could be down-regulated by inhibition of KRAS expression. Our results indicate that CREG1 is a down-stream effector of KRAS in a sub-type of NSCLC cells and a novel candidate biomarker or therapeutic target for KRAS mutant NSCLC.

Citreoviridin inhibits cell proliferation and enhances apoptosis of human umbilical vein endothelial cells

In some areas of China, citreoviridin (CIT) is considered one of the risk factors for development of cardiovascular disease (CVD). Apoptosis of endothelial cell may induce vascular endothelium injury and atherosclerosis, which result in CVD probably. In this study, we investigated the effect of CIT on apoptosis and proliferation of human umbilical vein endothelial cells (HUVECs). The MTT assay was used to determinate HUVECs proliferation. Distribution of the cell cycle was analyzed by flow cytometry. The Annexin-V/PI staining was used to investigate cell apoptosis. Western blotting analysis was used to indicate changes in the expression level of apoptosis-related proteins. The results indicated that CIT inhibited HUVECs proliferation and the cells were arrested at G0/G1 phase, which is associated with decreased levels of cyclinD1 and increased expression of p53 and p21. The apoptosis rate of HUVECs was improved by CIT. The expression of Bcl-2 were down-regulated after CIT treatment, whereas the levels of Bax was significantly up-regulated. Furthermore, CIT-induced apoptosis was accompanied by the activation of caspase-3, -9. These findings demonstrate that CIT inhibits cell proliferation via DNA synthesis reduction and induces caspase-dependent apoptosis in HUVECs. CIT plays a pivotal role in the process of endothelial cell apoptosis, may thereby play an important role in the improvement of CVD in areas of China that have a high prevalence of CIT contamination.

Bradykinin preconditioning improves therapeutic potential of human endothelial progenitor cells in infarcted myocardium

Objectives

Stem cell preconditioning (PC) is a powerful approach in reducing cell death after transplantation. We hypothesized that PC human endothelial progenitor cells (hEPCs) with bradykinin (BK) enhance cell survival, inhibit apoptosis and repair the infarcted myocardium.

Methods

The hEPCs were preconditioned with or without BK. The hEPCs apoptosis induced by hypoxia along with serum deprivation was determined by annexin V-fluorescein isothiocyanate/ propidium iodide staining. Cleaved caspase-3, Akt and eNOS expressions were determined by Western blots. Caspase-3 activity and vascular endothelial growth factor (VEGF) levels were assessed in hEPCs. For invivo studies, the survival and cardiomyocytes apoptosis of transplanted hEPCs were assessed using 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindodi- carbocyanine,4-chlorobenzenesul-fonate salt labeled hEPCs and TUNEL staining. Infarct size and cardiac function were measured at 10 days after transplantation, and the survival of transplanted hEPCs were visualized using near-infrared optical imaging.

Results

Invitro data showed a marked suppression in cell apoptosis following BK PC. The PC reduced caspase-3 activation, increased the Akt, eNOS phosphorylation and VEGF levels. Invivo data in preconditioned group showed a robust cell anti-apoptosis, reduction in infarct size, and significant improvement in cardiac function. The effects of BK PC were abrogated by the B2 receptor antagonist HOE140, the Akt and eNOS antagonists LY294002 and L-NAME, respectively.

Conclusions

The activation of B2 receptor-dependent PI3K/Akt/eNOS pathway by BK PC promotes VEGF secretion, hEPC survival and inhibits apoptosis, thereby improving cardiac function invivo. The BK PC hEPC transplantation for stem cell-based therapies is a novel approach that has potential for clinical used.

CREG promotes the proliferation of human umbilical vein endothelial cells through the ERK/cyclin E signaling pathway

Cellular repressor of E1A-stimulated genes (CREG) is a recently discovered secreted glycoprotein involved in homeostatic modulation. We previously reported that CREG is abundantly expressed in the adult vascular endothelium and dramatically downregulated in atherosclerotic lesions. In addition, CREG participates in the regulation of apoptosis, inflammation and wound healing of vascular endothelial cells. In the present study, we attempted to investigate the effect of CREG on the proliferation of vascular endothelial cells and to decipher the underlying molecular mechanisms. Overexpression of CREG in human umbilical vein endothelial cells (HUVEC) was obtained by infection with adenovirus carrying CREG. HUVEC proliferation was investigated by flow cytometry and 5-bromo-2′-deoxy-uridine (BrdU) incorporation assays. The expressions of cyclins, cyclin-dependent kinases and signaling molecules were also examined. In CREG-overexpressing cells, we observed a marked increase in the proportion of the S and G2 population and a decrease in the G0/G1 phase population. The number of BrdU positively-stained cells also increased, obviously. Furthermore, silencing of CREG expression by specific short hairpin RNA effectively inhibited the proliferation of human umbilical vein endothelial cells (HUVEC). CREG overexpression induced the expression of cyclin E in both protein and mRNA levels to regulate cell cycle progression. Further investigation using inhibitor blocking analysis identified that ERK activation mediated the CREG modulation of the proliferation and cyclin E expression in HUVEC. In addition, blocking vascular endothelial growth factor (VEGF) in CREG-overexpressed HUVEC and supplementation of VEGF in CREG knocked-down HUVEC identified that the pro-proliferative effect of CREG was partially mediated by VEGF-induced ERK/cyclin E activation. These results suggest a novel role of CREG to promote HUVEC proliferation through the ERK/cyclin E signaling pathway.

Protective effect of the silkworm protein 30Kc6 on human vascular endothelial cells damaged by oxidized low density lipoprotein (Ox-LDL)

Although the 30K family proteins are important anti-apoptotic molecules in silkworm hemolymph, the underlying mechanism remains to be investigated. This is especially the case in human vascular endothelial cells (HUVECs). In this study, a 30K protein, 30Kc6, was successfully expressed and purified using the Bac-to-Bac baculovirus expression system in silkworm cells. Furthermore, the 30Kc6 expressed in Escherichia coli was used to generate a polyclonal antibody. Western blot analysis revealed that the antibody could react specifically with the purified 30Kc6 expressed in silkworm cells. The In vitro cell apoptosis model of HUVEC that was induced by oxidized low density lipoprotein (Ox-LDL) and in vivo atherosclerosis rabbit model were constructed and were employed to analyze the protective effects of the silkworm protein 30Kc6 on these models. The results demonstrated that the silkworm protein 30Kc6 significantly enhanced the cell viability in HUVEC cells treated with Ox-LDL, decreased the degree of DNA fragmentation and markedly reduced the level of 8-isoprostane. This could be indicative of the silkworm protein 30Kc6 antagonizing the Ox-LDL-induced cell apoptosis by inhibiting the intracellular reactive oxygen species (ROS) generation. Furthermore, Ox-LDL activated the cell mitogen activated protein kinases (MAPK), especially JNK and p38. As demonstrated with Western analysis, 30Kc6 inhibited Ox-LDL-induced cell apoptosis in HUVEC cells by preventing the MAPK signaling pathways. In vivo data have demonstrated that oral feeding of the silkworm protein 30Kc6 dramatically improved the conditions of the atherosclerotic rabbits by decreasing serum levels of total triglyceride (TG), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C) and total cholesterol (TC). Furthermore, 30Kc6 alleviated the extent of lesions in aorta and liver in the atherosclerotic rabbits. These data are not only helpful in understanding the anti-apoptotic mechanism of the 30K family proteins, but also provide important information on prevention and treatment of human cardiovascular diseases.

Cellular repressor of E1A stimulated genes enhances endothelial monolayer integrity

Cellular repressor of E1A stimulated genes (CREG) is a novel modulator that maintains the homeostasis of vascular cells. The present study aimed to investigate the effects of CREG on tumor necrosis factor (TNF)-α-mediated inflammatory injury of vascular endothelial cells. Human umbilical vein endothelial cells (HUVECs) were cultured and CREG overexpressing (VC), knockdown (VS) and mock-transfected (VE) HUVECs were challenged with TNF-α. We demonstrated that TNF-α prompted robust intercellular filamentous actin (F-actin) stress fiber formation as examined by rhodamin-phalloidin staining. Transwell assay and rhodamine B isothiocyanate-dextran staining indicated that TNF-α induced intercellular hyperpermeability of the HUVEC monolayers. These effects were attenuated in VC cells with forced CREG overexpression but significantly potentiated in VS cells with CREG silencing. After TNF-α stimulation, interleukin (IL)-6 and IL-8 secretions in VE cells were markedly increased and inducible nitric oxidase (iNOS) expression substantially elevated, whereas these effects were pronouncedly damped in VC cells. Conversely, in VS cells, the increase in inflammatory markers was substantially potentiated. Immunofluorescence staining demonstrated that nuclear factor κB (NF-κB) slowly and transiently translocated into the nuclei of VC cells upon TNF-α stimulation. However, a more swift and sustained nuclear translocation was observed in VS as compared to VE cells. Corresponding changes in the pattern of its protein expression was also observed. These data suggested that CREG can inhibit NF-κB activation, TNF-α-induced inflammatory responses and the hyperpermeability of endothelial cells, and may therefore represent a potential therapeutic target for pathological vascular injury.

Nanoporous CREG-eluting stent attenuates in-stent neointimal formation in porcine coronary arteries

Background

The goal of this study was to evaluate the efficacy of a nanoporous CREG-eluting stent (CREGES) in inhibiting neointimal formation in a porcine coronary model.

Methods

In vitro proliferation assays were performed using isolated human endothelial and smooth muscle cells to investigate the cell-specific pharmacokinetic effects of CREG and sirolimus. We implanted CREGES, control sirolimus-eluting stents (SES) or bare metal stents (BMS) into pig coronary arteries. Histology and immunohistochemistry were performed to assess the efficacy of CREGES in inhibiting neointimal formation.

Results

CREG and sirolimus inhibited in vitro vascular smooth muscle cell proliferation to a similar degree. Interestingly, human endothelial cell proliferation was only significantly inhibited by sirolimus and was increased by CREG. CREGES attenuated neointimal formation after 4 weeks in porcine coronary model compared with BMS. No differences were found in the injury and inflammation scores among the groups. Scanning electron microscopy and CD31 staining by immunohistochemistry demonstrated an accelerated reendothelialization in the CREGES group compared with the SES or BMS control groups.

Conclusions

The current study suggests that CREGES reduces neointimal formation, promotes reendothelialization in porcine coronary stent model.

MicroRNA let-7c inhibits Bcl-xl expression and regulates ox-LDL-induced endothelial apoptosis

Endothelial cells (ECs) apoptosis induced by oxidized low-density lipoprotein (ox-LDL) is thought to play a critical role in atherosclerosis. MicroRNAs (miRNAs) are a class of noncoding RNAs that posttranscriptionally regulate the expression of genes involved in diverse cell functions, including differentiation, growth, proliferation, and apoptosis. MiRNA let-7 family is known to be involved in the regulation of cell apoptosis. However, the function of let-7 in ox-LDL induced ECs apoptosis and atherosclerosis is still unknown. Here, we show that let-7c expression was markedly up-regulated in ox-LDL induced apoptotic human umbilical cord vein endothelial cells (HUVECs). Let-7c over-expression enhanced apoptosis in ECs whereas inhibition of let-7c could partly alleviate apoptotic cell death mediated by ox-LDL. Searching for how let-7c affected apoptosis, we discovered that antiapoptotic protein Bcl-xl was a direct target of let-7c in ECs. Our data suggest that let-7c contributes to endothelial apoptosis through suppression of Bcl-xl.