Glycosylation-independent binding to extracellular domains 11-13 of mannose-6-phosphate/insulin-like growth factor-2 receptor mediates the effects of soluble CREG on the phenotypic proliferation of vascular smooth muscle cells

Background The present study aimed to investigate the detailed mode and specific sites for their binding as well as the functional relevance of this binding in the phenotypic proliferation of vascular smooth muscle cells(SMCs). Methods CREG knocked-down SMCs were employed to evaluate the biological activity of wtCREG and mCREG.Expressions of SMC differentiation markers SM myosin heavy chain(SM-MHC),SM-actin,heavy caldesmon and myocardin were determined by Western blotting using specific antibodies. Cellular growth of SMCs was assessed by bromide dewuridine (BrdU) incorporation and cell cycle analysis on fluorescence-activated cell sorting(FACS).A solid-phase binding assay was used to study the binding of CREG to extracellular domains of M6P/IGF2R.The cellular co-localization of the two recombinant CREGs with M6P/IGF2R was detected on SMC surface by immunoprecipitation and immunofluorescence analysis.Results The molecular weight of wtCREG was around 30 kD while that of the mCREG was～25 kD.Treatment of wtCREG with PNGase F reduced its molecular weight from～30 kD to～25 kD,whereas PNGase F treatment had no effect on the molecular weight of mCREG.Both wtCREG and mCREG proteins enhanced SMC differentiation,inhibited BrdU incorporation,and arrested cell cycle progression when added to the culture medium.In CREG knocked-down SMCs,the amount of CREG detected by immunoblotting in M6P/IGF2R immunoprecipitates was significantly reduced when compared to normal cells.Both recombinant CREGs co-immunoprecipitated with M6P/IGF2R, although slightly reduced amount of the mutant CREG was detected in M6P/IGF2R immunoprecipitates.Immunostaining revealed that His-tagged CREGs co-localized with IGF2R on the cell surface in a glycosylation-independent manner.In vitro binding assay showed that CREGs bound to M6P/ IGF2R extracellular domains 7-10 and 11-13 in a glycosylation -dependent and -independent manner,respectively.Further blocking experiments using soluble M6P/IGF2R fragments and M6P/IGF2R neutralizing antibody indicated that the biological activities of recombinant CREGs in SMC growth and the up-regulation of SMC differentiation markers were all abolished by treatment with the M6P/IGF2R neutralizing antibody. However,although the growth inhibitory effect of wtCREG was nearly abolished by D7-10 or D11-13,the effect of mCREG was only reversed by Dll-13,indicating that the binding to domains 11-13 is required for CREG to modulate the proliferation of SMCs.Conclusions These data suggest that solubleCREG proteins can exert their biological function via binding to the extracellular domains 7-10 and 11-13 of cell surface M6P/IGF2R in both a glycosylation-dependent and -independent manner.

RELATIONSHIP BETWEEN VASCULAR ENDOTHELIAL GROWTHFACTOR EXPRESSION AND ANGIOGENESIS AND CELLPROLIFERATION OF MALIGNANTGLIOMAS IN CHILDREN

Objective: To investigate the relation of vascular endothelial growth factor (VEGF) expression with angiogenesis and cell proliferation in malignant glioma in children. Methods: Immunohistochemical technique was used to detect the expression of VEGF, microvessel quantity (MVQ) and PCNA Labeling Index (PCNA LI) in 33 malignant gliomas in children Results: Positive staining for VEGF was obtained in 23 out of the 33 cases (69.7). The MVQ and PCNA LI in VEFG-positive tumors were significantly higher than those in VEGF-negative tumors (P<0.005). The expression of VEGF in tumor tissues was significantly correlative with MVQ and PCNA LI (r=0.52 and 0.37, respectively, P<0.001). Conclusion: VEGF can be synthesized in tumor cells of malignant glioma in children which might play a significant role in angiogenesis and cell proliferation in the tumor.

Influence of Stent Implantation on the Expression of PCNA and Apoptosis in Injured Vascular Smooth Muscle Cells

Objectives To evaluate the impact of stent implantation on proliferation and apop-tosis in injured media vascular smooth muscle cells (VSMC) and to explore the mechanism of restenosis after stent implantation. Methods Fifty male New Zealand rabbits were randomized into two groups, including balloon group and stent group. Control group was set up. The samples were harvested on 3, 7, 14, 28, 56 days after operation and the following investigation was carried out: (1) Assessing the expression of proliferating cell nuclear antigen (PCNA) of media VSMC by the method of immunohistochemistry; (2) Analyzing apoptosis of media VSMC by DNA agarose gel electrophoresis and TUNEL technique. Results The expression of PCNA and apoptosis in stent and balloon groups were markedly increased compared with control groups. (1) Stent group induced significant increased expression of PCNA in the media VSMC compared with balloon group on 3 to 28 days. On day 7, the positive rates of PCNA were 24. 36±0. 55 % vs 18. 74±1. 09 % ( P < 0. 01 ); (2) From 3 to 28 days, stent group appeared obvious DNA ladder, while balloon group only had little trace ; (3) TUNEL method showed that stent group induced much more significant apoptosis than that of balloon group on 3 to 28 days. The highest rate of apoptosis appeared on day 7: 12. 42 ±1.13% vs 5. 54±0.53% (P<0. 01); (4) By calculating the ratio of the positive rate of PCNA to apoptosis, it showed that on 3 to 28 days, the ratio of balloon group was higher than that of stent group. There was obvious difference between two groups. Conclusions Stent group induces augmented proliferation and much more significant apoptosis of media VSMC than that of balloon group. It makes the ratio of proliferation to apotosis reduced and the severity of restenosis relieved after stent implantation.

Rutaecarpine attenuates monocrotaline-induced pulmonary arterial hypertension in a Sprague-Dawley rat model

Background:Pulmonary arterial hypertension presents with obliterative remodeling of the pulmonary arteries and progressive elevation of pulmonary vascular resistance,which increase the risk of right ventricular failure and death.It has been reported in previous studies that rutaecarpine plays a crucial role in anti-inflammatory and antioxidant activities,which may help regulate cell apoptosis and cell proliferation.The purpose of this study was to determine the effects of rutaecarpine in the rat model of monocrotaline-induced pulmonary hypertension.Methods:We induced pulmonary arterial hypertension in adult Sprague-Dawley rats by injecting monocrotaline(60 mg/kg)and then treated with rutaecarpine(40 mg/kg·d)or sildenafil(30 mg/kg·d)(positive control).Subsequently,pulmonary function,inflammation,cytokines and pulmonary vascular remodeling or proliferation were assessed.Results:Rutaecarpine was found to improve monocrotaline-induced mean pulmonary artery pressure,cardiac index,right heart index,right ventricular hypertrophy index,pulmonary artery remodeling and pulmonary function.reverse transcription-quantitative polymerase chain reaction demonstrated a decrease in tumor necrosis factor-α,interleukin-6 and interleukin-1β,whereas western blots a significantly decrease in the expression of nuclear factor kappa-B,endothelin-1,extracellular signal-regulated kinases 1/2,B cell lymphoma-2,Beclin1 and microtubule-associated protein1 light chain 3-II protein,and increase in the expression of Bax,caspase-3 and p62 protein.Conclusion:Rutaecarpine attenuated pulmonary arterial hypertension by inhibiting inflammation,oxidative stress,cell proliferation and autophagy,while promoting apoptosis.

Rutaecarpine Inhibits Angiotensin Ⅱ-Induced Proliferation in Rat Vascular Smooth Muscle Cells

Objective： To evaluate the effects and possible mechanisms of rutaecarpine on angiotensin Ⅱ （Ang Ⅱ ）-induced proliferation in cultured rat vascular smooth muscle cells （VSMCs）. Methods： VSMCs were isolated from Male Sprague-Dawley rat aorta, and cultured by enzymic dispersion method. Experiments were performed with cells from passages 3-8. The cultured VSMCs were randomly divided into control, model （Ang Ⅱ 0.1 μ moVL）, and rutaecarpine （0.3-3.0μmol/L） groups. VMSC proliferation was induced by Ang Ⅱ, and was evaluated by the 3-（4, 5-dimethylthiazol-2-yl）-2, 5-diphenyltetrazolium bromide assay and cell counting. To examine the mechanisms involved in anti-proliferative effects of rutaecarpine, nitric oxide （NO） levels and NO synthetase （NOS） activity were determined. Expressions of VSMC proliferation-related genes including endothelial nitric oxide synthase （eNOS）, and c-myc hypertension related gene-1 （HRG-1） were determined by real-time reverse chain reaction （RT-PCR）. Results： Rutaecarpine （0.3-3.0μmol/l_） inhibited Ang R-induced VSMC proliferation and the best effects were achieved at 3.0 μmol/L. The Ang Ⅱ-induced decreases in cellular NO contents and NOS activities were antagonized by rutaecarpine （P〈0.05）. Ang Ⅱ administration suppressed the expressions of eNOS and HRG-1, while increased c-myc expression （P〈0.05）. All these effects were attenuated by 3.0μmol/L rutaecarpine （P〈0.05）. Conclusion： Rutaecarpine is effective against Ang Ⅱ-induced rat VSMC proliferation, and this effect is due, at least in part, to NO production and the modulation of VMSC proliferation-related gene expressions.

Inhibition of vascular smooth muscle cell proliferation by in troduction of retinoblastoma gene via a recombinant adenovirus vector

This study was supported in part by grant from National Natural Science Foundation of China (No. 39570775). Objective To investigate the vascular smooth muscle cell (SMC) growth suppression by recombinant adenovirus vector expressing a retinoblastoma (Rb) protein and to explore a gene therapy approach for vascular proliferative disorders including atherosclerosis and artery restenosis. Methods A replication deficient adenovirus vector encoding a wild type Rb and AdCMVRb, was constructed and transfected into cultured rabbit aortic SMC. The efficiency of gene transfection and expression was detected by immunochemical staining and polymerase chain reaction. The role of Rb in regulating vascular SMC proliferation was observed by cell counting, thymidine incorporation, and flow cytometry. Results Wild type Rb gene transfected effectively into the cultured SMC with AdCMVRb can suppress growth factor stimulated cell proliferation through regulation of DNA synthesis and cell cycle progression. Conclusion The results demonstrate the potential of adenovirus mediated Rb gene therapy for atherosclerosis and artery restenosis after balloon angioplasty.

Effect of Aloe Emodin on Proliferation of Vascular Smooth Muscle Cells after Arterial Injury

Objective: To study the effect of Aloe emodin (AE), an active ingredient of Rhubarb,on the kinetics of proliferation of smooth muscular cells (SMCs) cultured in vitro after rabbit iliac arterial injury. Methods: Forty-eight hours after de-endothelialization (balloon endothelial denudation), the iliac arteries of the Japanese white rabbits were isolated and the smooth muscle cells were cultured primarily.AE was added to culture medium containing 10% fetal calf serum (FCS ). The cultures were pulse-labeled with 3H-TdR and TdR uptake into VSMC were measured and the cell cycle of the cultures were analyzed by using flow cytometer. Results: Compared with control, when the concentration gradient ranged from 10 - 1 to 10-5 g/L, the amount (cpm,count per minute) of 3H-TdR uptake into SMCs has significant differences (P < 0. 05 )and 10 -1 and 10 -2 g/L AE showed strong inhibitory effects on TdR uptake into VSMC and the percentage of inhibition [% inhibition =(cpm without AE-cpm with AE)/cpm without AE] was more than 90%. AE displayed concentration dependent inhibitory effects. The percentage of cells in G0/G1 phase was increased, but the percentage of cells in S phase was decreased in AE group, the transition of SMC cycle phase from G0 to S was blocked.Conclusion: AE is a strong inhibitor to the proliferation of SMCs and the pharmacological action of AE may reduce SMC proliferation in vivo and decrease intimal hyperplasia of restenosis.Original article on CJIM(Chin) 1998; 18(7): 420

Shexiang Baoxin Pill Regulates Intimal Hyperplasia,Migration,and Apoptosis after Platelet-Derived Growth Factor-BB-Stimulation of Vascular Smooth Muscle Cells via miR-451

Objective:To investigate the regulatory roles of Shexiang Baoxin Pill(SXBXW)in neointimal formation and vascular smooth muscle cells(VSMCs)invasion and apoptosis as well as the potential molecular mechanisms using cultured VSMCs model of vascular injury(platelet-derived growth factor(PDGF)-BBstimulated)in vitro.Methods:VSMCs were randomly assigned to 5 groups:blank,PDGF-BB(20 ng/mL+0.1%DMSO),SXBXW-L(PDGF-BB 20 ng/mL+SXBXW low dose 0.625 g/L),SXBXW-M(PDGF-BB 20 ng/mL+SXBXW medium dose 1.25 g/L)and SXBXW-H(PDGF-BB 20 ng/mL+SXBXW high dose 2.5 g/L)group.Cell proliferation was assessed using cell counting kit-8(CCK-8)assay and bromodeoxyuridine(BrdU)incorporation assay,the migration effects were detected by Transwell assay,cell apoptosis rate was measured by the Annexin V/propidium iodide(PI)apoptosis kit.The markers of contractile phenotype of VSMCs were detected with immunofluorescent staining.To validate the effects of miR-451 in regulating proliferation,migration and apoptosis treated with SXBXW,miR-451 overexpression experiments were performed,the VSMCs were exposed to PDGF-BB 20 ng/mL+0.1%DMSO and later divided into 4 groups:mimic-NC(multiplicity of infection,MOI=50),SXBXW(1.25 g/L)+mimic-NC,mimic-miR451(MOI=50),and SXBXW(1.25 g/L)+mimic-miR451,and alterations of proteins related to the miR-451 pathway were analyzed using Western blot.Results:PDGF-BB induced VSMCs injury causes acceleration of proliferation and migration.SXBXW inhibited phenotypic switching,proliferation and migration and promoted cell apoptosis in PDGF-BB-induced VSMCs.In addition,miR-451 was shown to be down-regulated in the VSMCs following PDGF-BB stimulation.SXBXW treatment enhanced the expression of miR-451 in PDGF-BB-induced VSMCs(P<0.05).Compared with SXBXW+mimic-NC and mimicmiR451 groups,the expression of tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein zeta(Ywhaz)and p53 was further reduced in SXBXW+mimic-miR451 group,while activating transcription factor 2(ATF2)was increased in VSMCs(P<0.05).Conclusion:SXBXW regulated proliferation,migration and apoptosis via activation of miR-451 through ATF2,p53 and Ywhaz in PDGF-BB-stimulated VSMCs.