INHIBITORY EFFECT OF ANGIOTENSIN Ⅱ TYPE 1 RECEPTOR-ASSOCIATED PROTEIN ON VASCULAR SMOOTH MUSCLE CELL GROWTH AND NEOINTIMAL FORMATION

Objective To investigate the mechanism of a novel angiotensin n type 1 receptor-associated protein (ATRAP) interfering with angiotensin Ⅱ type 1 (AT1) receptor-mediated vascular smooth muscle cell (VSMC) growth and neointimal formation. Methods VSMCs isolated from thoracic aorta of adult Sprague-Dawley ( SD) rats were used in this study. ATRAP Cdna was subcloned into pcDNA3 vector and then transfected into VSMCs. DNA synthesis and extracellular signal-regulated kinase (ERK) and phospho-ERK expressions in VSMCs were assayed by measurement of 3H thymidine incorporation and Western blotting, respectively. Morphological changes were observed in the balloon injured artery with or without transfection of ATRAP Cdna using 12-week-old male SD rats. Results ATRAP overexpression in VSMCs inhibited angiotensin Ⅱ (Ang Ⅱ) -induced 3H thymidine incorporation 48 hours after Ang Ⅱ stimulation (P ＜ 0.05). In VSMC, Ang Ⅱ stimulation increased the phosphorylation of ERK, which reached the peak around 60 minutes. The activation of phospho-ERK was significantly decreased by ATRAP (P ＜ 0.05). Neointimal formation was markedly inhibited by ATRAP overexpression in injuried arteries. Conclusions The AT1 receptor-derived activation of ERK plays an essential role in Ang Ⅱ-induced VSMC growth. The growth inhibitory effects of ATRAP might be due to interfering with AT1 receptor-mediated activation of ERK in VSMC growth and neointimal formation.     

Effect of angiotensin Ⅱ and angiotensin Ⅱ type 1 receptor antagonist on the proliferation,contraction and collagen synthesis in rat hepatic stellate cells

Background Angiotensin Ⅱ （Ang Ⅱ） is a very important vasoactive peptide that acts upon hepatic stellate cells （HSCs）, which are major effector cells in hepatic cirrhosis and portal hypertension. The present study was aimed to investigate the effects of Ang Ⅱ and angiotensin Ⅱ type 1 receptor antagonist （AT1RA） on the proliferation, contraction and collagen synthesis in HSCs.
Methods HSC-T6 rat hepatic stellate cell line was studied. The proliferation of the HSC cells was evaluated by MTT colorimetric assay while HSC DNA synthesis was measured by ^3H-thymidine incorporation. The effects of angiotensin Ⅱ and AT1RA on HSCs contraction were studied by analysis of the contraction of the collagen lattice. Cell culture media were analyzed by RT-PCR to detect secretion of collagen Ⅰ （Col Ⅰ）, collagen Ⅲ （Col Ⅲ） and transforming growth factor β1 （TGF-β1） by enzyme linked immunosorbent assay. HSC was harvested to measure collagen Ⅰ, collagen Ⅲ and tissue inhibitor of metalloproteinase-1 （TIMP-1） mRNA expression.
Results Ang Ⅱ （（1×10^-10-1×10^-4）mol/L）stimulated DNA synthesis and proliferation in HSCs compared with untreated control cells. AT1RA inhibited angiotensin Ⅱ induced proliferation of HSCs. A linear increase in the contractive area of collagen lattice correlated with the concentration of angiotensin Ⅱ （1×10^-9-1×10^-5 mol/L） and with time over 48 hours. AT1RA blocks angiotensin Ⅱ induced contraction of collagen lattice. Col Ⅰ, Col Ⅲ and TGF-β1 levels of the Ang Ⅱ group were higher than those of control group and this increase was downregulated by AT1RA. The mRNA expressions of Col Ⅰ, Col Ⅲ and TIMP-1 were higher in HSCs from the Ang Ⅱ group than the control group and downregulated by AT1RA.
Conclusions Angiotensin Ⅱ increased DNA synthesis and proliferation of HSCs in a dose-dependent manner, stimulated the contraction of HSCs dose- and time-dependently. Angiotensin also promoted excretion of Col I, Col Ⅲ and TGF-β1 lev     

Effect of Sodium Tanshinone ⅡA Sulfonate on Phosphorylation of Extracellular Signal-regulated Kinasel/2 in Angiotensin Ⅱ-induced Hypertrophy of Myocardial Cells

Objective： To observe the effects of sodium tanshinone ⅡA sulfonate （STS） on angiotensin Ⅱ （Ang Ⅱ）-induced hypertrophy of myocardial cells through the expression of phosphorylated extracellular signal-regulated kinase （p-ERK1/2）. Methods： In the primary culture of neonatal rat myocardial cells, the total protein content in myocardial cells was determined by coomassie brilliant blue and the protein synthesis rate was measured by [3H]-Leucine incorporation as indexes for hypertrophy of myocardial cells. The expression of p-ERK1/2 was determined using Western blot and immunofluorescence labeling. Results： （1） The total protein and protein synthesis rate increased significantly in contrast to the control group after the myocardial cells were stimulated by Ang Ⅱ （1 μ mol/L） for 24 h; STS markedly inhibited the increment of the total protein level induced by Ang Ⅱ and the syntheses of protein. （2） After pretreatment of myocardial cells with Ang Ⅱ （1 μmol/L） for 5 min, the p-ERK1/2 protein expression was increased, with the most obvious effect shown at about 10 min; pretreatment of myocardial cells with STS at different doses （2, 10, 50μmol/L） for 30 min resulted in obvious inhibition of the expression of p-ERK1/2 stimulated by Ang Ⅱ in a dose-dependent manner. （3） After the myocardial cells were stimulated by AngⅡ （1 μ mol/L）, the immunofluorescence of ERK1/2 rapidly appeared in the nucleus. The activation and translocation process of ERK1/2 induced by Ang Ⅱ was blocked distinctly by STS. （Conclusion： STS inhibited the myocardial cell hypertrophy induced by Ang Ⅱ, and the mechanism may be associated with the inhibition of p-ERK1/2 expression.     

The mechanism of signal transduction during vascular smooth muscle cell proliferation induced by autoantibodies against angiotensin AT1 receptor from hypertension

Background Autoantibodies against angiotensin AT1 receptor have been discovered in patients with preeclampsia or malignant hypertension. Some studies have demonstrated that the autoantibodies are involved in the immunopathogenesis of hypertension and have an agonist effect similar to angiotensin II. Methods Autoantibodies against AT1 receptor were purified from sera of patients with primary hypertension by affinity chromatography. Proliferation of cultured rat vascular smooth muscle cells was detected by bromodeoxyuridine incorporation and activation of signalling molecules detected by Western blotting and electrophoretic mobility shift assay. Results The AT1-RAb caused a significant proliferation similar to the Ang II during first 24 hours. The levels of nuclear factor-KB （NF-KB）, phosphorylated JAK2., phosphorylated STAT1 （pSTAT1） and phosphorylated STAT3 （pSTAT3） molecules were increased in response to the autoantibodies. In contrast, the activations of NF-KB and JAK-STAT were blocked by Iosartan, pyrrolidinedithiocarbamate （a specific inhibitor of NF-KB） and AG490 （a specific inhibitor of the JAK2. tyrosine kinase）. The expressions of NF-KB, pSTAT1 and pSTAT3 reached peak levels at different times. Moreover, the relative densities of electrophoretic bands showed that activation of pSTAT3 was more significant than STAT1 induced by AT1 -RAb. Conclusions These results suggest that the autoantibodies against AT1 receptor have an agonist effect similar to Ang II in proliferation of VSMCs and the NF-KB and JAK-STAT proteins play essential roles. The effect is different from Angll in that STAT3 is the main downstream activating molecule in JAK-STAT signalling pathway.     

Recent advances and findings of angiotensin type 2 receptor: a review

Angiotensinogen is a member of the serpin family. It is produced constitutively and released into the circulation mainly by the liver. Angiotensinogen forms angiotensin Ⅰ by action of the circulated renin released from the kidney. Angiotensin Ⅱ （Ang Ⅱ）, an octapeptide hormone with sequence Asp-Arg-Val-Tyr-Ile-His-Pro-Phe,is converted from angiotensin Ⅰ through removal of two terminal residues by the angiotensin-converting enzyme （ACE） mostly catalyzed in the lung.1 This peptide binds to two subtype receptors, angiotensin type 1 receptor （AT1R） and angiotensin type 2 receptor （AT2R）,members of the superfamily of heptahelical G protein coupled receptors, with different affinities.2 It is well known that AT1R and AT2R crosstalk and lead to counterregulatory functions in many systems, especially the cardiovascular system.3 Accumulating data established the roles of AT1R in the classic actions of Ang Ⅱ including vasoconstriction and cardiovascular hypertrophy, whereas AT2R is suggested to exert direct functions in vasodilation and antigrowth effects.4 Recent publications provide new insights into the roles of AT2R with increasing responsibilities. Recent progresses in AT2R research are reviewed in this article.     

Role of angiotensin Ⅱ receptore in proliferation of fibroblast derived from human hypertrophic

Objective The present study was undertaden to observe the expression of angiotensin Ⅱ （Ang Ⅱ） type 1 （AT1） and type 2 （AT2） receptors in human hypertrophic scars,and explore their role in the proliferation of fibroblasts in human hypertrophic scars.Methods The expression of both AT1 and AT2 receptors in fibroblasts of hypertrophic scars was detected with immunohistochemical staining.     

Role of angiotensin Ⅱ and angiotensin Ⅱ receptors in vascular smooth muscle cell migration in vitro

ObjectiveTo determine the biotic effects of angiotensin Ⅱ (Ang Ⅱ) on the migration of rat smooth muscle cells (VSMCs) and investigate the mechanisms involved in the development of vascular injury. Methods VSMCs isolated from aortic media of Wistar rats and cultured by the modified explant method were adopted. In the presence and absence of Ang Ⅱ, the expression of Ang Ⅱ receptor (ATR) and reorganization of the actin cytoskeleton and focal adhesion of VSMCs were studied by an immunocytochemistry technique and fluorocytochemistry technique. Migration assays were performed with a modified Boyden’s chamber. The effects of AT(1)R antagonist (CV- 11974), AT2R antagonist (PD123319) on the aforementioned target were studied. Results VSMCs migration was stimulated by adding Ang Ⅱ. The dynamic reorganization of actin cytoskeleton and focal adhesions may be an important mechanism by which Ang Ⅱ facilitates VSMCs motility. The expression of AT(1)R in VSMCs could be upregulated initially after treatment with Ang Ⅱ, then decreased gradually. The expression of AT(1)R was downregulated by AT(1)R antagonists. The effect of Ang Ⅱ on VSMCs migration was mediated by AT(1)R, while AT2R had no significant effect. Conclusions The dynamic reorganization of focal adhesions and the actin cytoskeleton is required for Ang Ⅱ- induced VSMCs migration. This effect is mediated by AT(1)R.     

Nardosinone protects H9c2 cardiac cells from angiotensin II-induced hypertrophy

Pathological cardiac hypertrophy induced by angiotensin Ⅱ （Ang Ⅱ ） can subsequently give rise to heart failure, a leading cause of mortality. Nardosinone is a pharmacologically active compound extracted from the roots ofNardostachys chinensis, a well-known traditional Chinese medicine. In order to investigate the effects of nardosinone on Ang Ⅱ-induced cardiac cell hypertrophy and the related mechanisms, the myoblast cell line H9c2, derived from embryonic rat heart, was treated with nardosi- none （25, 50, 100, and 200μmol/L） or Ang Ⅱ （1 μmol/L）. Then cell surface area and mRNA expression of classical markers of hypertrophy were detected. The related protein levels in PI3K/Akt/mTOR and MEK/ERK signaling pathways were examined by Western blotting. It was found that pretreatment with nardosinone could significantly inhibit the enlargement of cell surface area induced by Ang Ⅱ. The mRNA expression of ANP, BNP and 13-MHC was obviously elevated in Ang Ⅱ-treated H9c2 cells, which could be effectively blocked by nardosinone at the concentration of 100μmol/L. Further study revealed that the protective effects of nardosinone might be mediated by repressing the phosphorylation of related proteins in PI3K/Akt and MEK/ERK signaling pathways. It was suggested that the inhibitory effect of nardosinone on Ang Ⅱ-induced hypertrophy in H9c2 cells might be mediated by targeting PI3K/Akt and MEK/ERK signaling pathways.     

Dahuang Zhechong Pill (大黄虫丸) containing serum inhibited platelet-derived growth factor-stimulated vascular smooth muscle cells proliferation by inducing G1 arrest partly via suppressing protein kinase C α-Extracellular regulated kinase 1/2 signaling pathway

Objective:To investigate effects of Dahuang Zhechong Pill（大黄（?）虫,DHZCP） on the cell cycle and the related signal pathways in vascular smooth muscle cells（VSMCs） stimulated by platelet-derived growth factor（PDGF） with the method of serum pharmacology.Methods:DNA synthesis in VSMCs was examined by detecting 5’-bromo-2’-deoxyuridine incorporation with the immunocytochemical method.The cycle of VSMCs was evaluated with flow cytometry.Expressions of cyclin D1,p27,protein kinase Cα（PKCα）,and phosphorylated extracellular signal regulated kinase 1/2（ERK1/2） were quantified by Western blot method. Results:DHZCP containing serum significantly inhibited DNA synthesis of PDGF-stimulated VSMCs,arrested the cells in G₁ phase,modulated the protein expressions of cyclin D₁ and p27,and suppressed the activation of PKCαand ERK1/2.Conclusion:DHZCP containing serum inhibits VSMCs proliferation via modulating the expressions of cell cycle proteins to arrest the cell in G₁ phase,which is attributed to,at least in part,suppressing PKCα-ERK1/2 signaling in VSMCs.     

Rapamycin Treatment Attenuates Angiotensin II -induced Abdominal Aortic Aneurysm Formation via VSMC Phenotypic Modulation and Down-regulation of ERK1/2 Activity

The aim of the present study is to address the effect of rapamycin on abdominal aortic aneurysm (AAA) and the potential mechanisms. A clinically relevant AAA model was induced in apolipoprotein E-deficient (ApoE-/-) mice, in which miniosmotic pump was implanted subcutaneously to deliver angiotensin II (Ang II) for 14 days. Male ApoE-/- mice were randomly divided into 3 groups: saline infusion, Ang II infusion, and Ang II infusion plus intraperitoneal injection of rapamycin. The diameter of the supra-renal abdominal aorta was measured by ultrasonography at the end of the infusion. Then aortic tissue was excised and examined by Western blotting and histoimmunochemistry. Ang n with or without rapamycin treatment was applied to the cultured vascular smooth muscle cells (VSMCs) in vitro. The results revealed that rapamycin treatment significantly attenuated the incidence of Ang II induced-AAA in ApoE-/- mice. Histologic analysis showed that rapamycin treatment decreased disarray of elastin fibers and VSMCs hyperplasia in the medial layer. Immunochemistry staining and Western blotting documented the increased phospho-ERK1/2 and ERK1/2 expression in aortic walls in Ang II induced-AAA, as well as in human lesions. Whereas in the rapamycintreated group, decreased phospho-ERKl/2 expression level was detected. Moreover, rapamycin reversed Ang II -induced VSMCs phenotypic change both in vivo and in vitro. Based on those results, we confirmed that rapamycin therapy suppressed Ang II -induced AAA formation in mice, partially via VSMCs phenotypic modulation and down-regulation of ERK1/2 activity.     

先兆子痫患者血清血管紧张素Ⅱ 1型受体自身抗体对血管平滑肌细胞ERK1/2信号途径的激动效应

目的探讨血管紧张素Ⅱ1型受体(AT1受体)的自身激动性抗体(AT1-AAs)激动培养的大鼠血管平滑肌细胞(VSMCs)AT1受体并激活细胞外信号调节激酶1/2(ERK1/2)信号途径的能力。方法采用亲和层析法提取先兆子痫患者血清中的AT1-AAs。培养大鼠主动脉VSMCs。应用血管紧张素Ⅱ(AngⅡ)或AT1-AAs刺激培养的细胞。而后,采用免疫印迹法测定细胞中ERK1/2的表达;逆转录PCR检测细胞c-fos基因的表达;应用钙离子的荧光探针Fluo-3/AM负载培养VSMCs,应用共聚焦显微镜检测细胞荧光强度变化以反映细胞内游离钙水平的变化。结果 AT1-AAs能够发挥与血管紧张素Ⅱ类似的效应,能够激动AT1受体,促使ERK1/2的磷酸化并促进其下游的c-fos在VSMCs中的表达;并且ERK1/2的磷酸化一定程度依赖于钙离子信号。结论由于ERK1/2信号通过促进血管炎症、纤维化及血管收缩造成血管重塑,AT1-AAs可能通过该途径参与先兆子痫患者的循环障碍。     

血管紧张素Ⅱ和血小板源生长因子对血管平滑肌和心肌细胞细胞周 …

目的 观察血管紧张素Ⅱ（ＡｎｇⅡ）和血小板源生长因子ＢＢ（ＰＤＧＦ－ＢＢ）对血管平滑肌细胞和心肌细胞中细胞周期素和Ｐ２７蛋白表达量的不同影响,方法 培养的血管平滑肌细胞或乳鼠心肌细胞,加入ＡｎｇⅡ１０＾－６ｍｏｌ／Ｌ,ＰＤＧＦ－ＢＢ２０ｎｇ／ｍｌ后２４小时收集细胞,用碘化丙啶（ＰＩ）标记细胞ＤＮＡ,以确定细胞所处的周期,用细胞周期素（ＣｙｃｌｉｎＤ,ＣｙｃｌｉｎＥ,ＣｙｃｌｉｎＡ）或Ｐ２７蛋白的单     

细胞周期蛋白质依赖激酶抑制因子在血管平滑肌细胞增殖与增生中的作用

目的探讨细胞周期蛋白依赖激酶抑制因子p27、p21和p57在血管平滑肌细胞(VSMC)增殖与增生过程中的调控作用.方法分离SD大鼠主动脉中层平滑肌,贴壁法培养平滑肌细胞,无血清培养基培养静止后,分别加入AngⅡ10-6mol/L,血小板源生长因子(PDGF)20ng/ml和10%FBS,在刺激后6、12、24h分别收集细胞,以无血清培养基培养的VSMC作静止对照,以10%FBS刺激的VSMC作增殖对照.用Westernblot分别检测p27、p57和p21蛋白表达量.结果在AngⅡ刺激的VSMC中,p21,p57和p27蛋白表达水平与静止的VSMC中相近,无明显变化(P>0.05);而在PDGF-BB刺激的VSMC中,p21蛋白表达量随刺激时间延长而逐渐增加,在刺激后12h开始增加,24h达高峰(A值为1.578±0.133,对照组A值为1.000±0.011,P<0.01);p57蛋白表达量在刺激24h增加(A值为1.641±0.342,对照组A值为1.000±0.016,P<0.01);p27蛋白表达量随刺激时间延长而逐渐下降,在24h下降最明显(A值为0.401±0.137,对照组A值为0.985±0.023,P<0.01).结论p21和p57的主要作用在于防止VSMC细胞过度增殖.p27蛋白表达量的变化是决定VSMC增殖的关键,并参与VSMC增生的诱导和维持.     

丝裂素活化蛋白激酶在AngⅡ上调培养的血管平滑肌细胞转化生长因子-β受体表达中的作用

目的:探讨丝裂素活化蛋白激酶在血管紧张素Ⅱ(AngⅡ)诱导血管平滑肌细胞(VSMC)转化生长因子-β受体(TGF-βR1)上调中的作用。方法:培养大鼠主动脉VSMC,以10-7mol/L AngⅡ刺激作为AngⅡ组,AngⅡ刺激前分别应用10-5mol/L氯沙坦(Losartan)、PD98059预处理,以正常的VSMC为对照组,细胞免疫化学法测定培养12h时VSMC TGF-βR1的含量。结果:与对照组相比,AngⅡ刺激培养12h的VSMC TGF-βR1表达上调(P<0.01);AngⅡ受体AT1型拮抗剂Losartan使TGF-βR1表达显著降低(P<0.01),丝裂素活化蛋白激酶抑制剂PD98059能显著降低TGF-βR1表达(P<0.05)。结论:AngⅡ通过AT1上调TGF-βR1的表达,丝裂原活化蛋白激酶参与AngⅡ的胞内信号转导。     

PP60c-Src在血管紧张素Ⅱ对大鼠血管平滑肌细胞信息转导中的作用

目的：通过观察c—Src在AngⅡ对大鼠血管平滑肌细胞(VSMC)丝裂原活化的蛋白激酶(MAPK)活性和c—fos蛋白表达的影响，以进一步了解AngⅡ促VSMC增殖的细胞内信息转导机制。方法：原代和传代培养SD大民主动脉VSMC，以脂质体包裹反义c—Src寡脱氧核夺酸(Oligodeoxynucleotides ODNs)转染培养的VSMC以抑制c—Src蛋白表达和激酶活性。以未转染的VSMC为对照，观察10^7mol/L AngⅡ刺激对转染的VSMC的MAPK活性和c—fos蛋白表达的影响。蛋白免疫沉淀和酶自身磷酸化率测定c—Src激酶活性；髓鞘碱性蛋白(MBP)底物磷酸化率测定MAPK放酶活性；Western blot免疫印迹法测定c—Src和c—fos蛋白表达情况。始果：转染不同浓度反义c—Src()DNs的VSMCc—Src蛋白含量至浓度依赖性降低，0.2μmol/L、0.5μmol/L、1．0μmol／L和2．0μmol/L分别为对照的68．2％、34．7％、30。3％和15．8％，经方差分析具有显著性意义(P＜0.01)。c—Src激酶活性也显著抑制；以AngⅡ刺激经转染反义c—Src DNs的VSMC，c—Src激酶活性增幅仅为对照组的8．7％；MAPK活性仅为对照的1．6％；c—fos蛋白表达的增幅为对照组的30．0％。结论：AngⅡ可诱导VSMC c—Src激活和细胞内信息转导，且AngⅡ引起的MAPK和c—fos的激活依赖于c—Src的激活，提示c—Src是AngⅡ促血管平滑细胞增殖的重要信息分于。     

同型半胱氨酸在大鼠血管平滑肌细胞上通过激活ERK1/2信号通路促进血管紧张素Ⅱ受体1表达

目的：在原代大鼠血管平滑肌细胞(VSMC)上观察同型半胱氨酸(Hcy)对血管紧张素II受体1(AT1R)的蛋白表达的影响。     

真核表达载体pEGFP-N2/AT2R的构建及其在原代血管平滑肌细胞的表达

目的体外构建携带血管紧张素Ⅱ2型受体(ANGⅡType 2 Receptor,AT2R)基因的增强型绿色荧光蛋白真核表达载体,并观察其在大鼠血管平滑肌细胞(vascular smooth muscle cells,VSMCs)中的表达。方法以pUHD-10.3/AT2R质粒为模板,PCR扩增AT2R基因的全长cDNA序列,再将其克隆入载体pEGFP-N2,构建其真核表达载体pEGFP-N2/AT2R。以基因转染技术,将AT2R导入原代VSMCs。倒置荧光显微镜观测转染后VSMCs生长变化及AT2R在其中的表达等情况。图像分析技术检测AT2R在VSMCs中的转染效率。Western blot检测转染AT2R基因的VSMCs表达其编码蛋白。RT-PCR法对AT2R基因修饰的VSMCs进行鉴定。结果成功构建AT2R基因的真核表达载体pEGFP-N2/AT2R,该真核载体能携带AT2R基因转染并有效表达于VSMCs,其转染效率约40%,RT-PCR及Western blot均可检测到AT2RmRNA及蛋白在血管平滑肌细胞中高表达。结论成功地将克隆到的AT2R基因克隆入pEGFP-N2载体中,并实现了AT2R基因在原代VSMCs的表达。