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.     

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.     

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。     

血管紧张素Ⅱ受体及其信号转导关键酶在宫颈癌中的表达

目的 探讨血管紧张素Ⅱ-1型受体（AT1R）和血管紧张素Ⅱ-2型受体（AT2R）及其信号转导关键酶在宫颈癌中的表达。方法 收集2013年3月～2014年2月河南省人民医院及中国医科大学航空总医院手术切除正常宫颈组织47例（对照组）、宫颈上皮内瘤变（CIN）组织36例（CIN组）及65例宫颈癌组织标本（宫颈癌组）。采用实时荧光定量PCR检测AT1R和AT2R mRNA水平;蛋白质印记法检测AT1R和AT2R蛋白表达水平。激活AT1R,测定酪氨酸激酶（PTK）活性;激活AT2R,测定胞浆型磷脂酶A2（cPLA2）活性。结果 与对照组比较,CIN组及宫颈癌组AT1R、AT2R的mRNA水平以及蛋白表达水平均明显升高,差异均有统计学意义（P〈0.05或P〈0.01）。激活AT1R后,CIN组与宫颈癌组的PTK活性与对照组比较均明显升高[（64.00±16.23）,（89.00±20.76）比（50.00±12.16）],差异均有统计学意义（P〈0.05或P〈0.01）;与CIN组比较,宫颈癌组进一步升高（P〈0.05）。激活AT2R后,CIN组和宫颈癌组的cPLA2活性与对照组比较均明显升高[（137.00±19.72）、（181.00±30.83）比（104.00±21.46）],差异均有统计学意义（P〈0.05或P〈0.01）;与CIN组比较,宫颈癌组进一步升高,差异有统计学意义（P〈0.05）。结论 AT1R、AT2R与宫颈癌的发生发展密切相关,有望成为宫颈癌潜在的诊断和治疗靶点。     

哮喘小鼠肺脏组织肾素-血管紧张素系统相关组分表达 及AT1R拮抗剂对其影响

目的：探讨肾素-血管紧张素系统（RAS）与哮喘发生的关系,为哮喘发病机制的研究和治疗提供理论依据。方法：复制小鼠哮喘模型,小鼠分为对照组、模型组、坎地沙坦低剂量组及高剂量组,采集小鼠血清,测量血清中血管紧张素Ⅱ (AngⅡ)与血管紧张素Ⅰ(AngⅠ)的含量;通过Western blotting和RT-PCR观察RAS中血管紧张素原(AGT)、血管紧张素转换酶(ACE)、血管紧张素Ⅱ 1型受体（AT₁R）和2型受体（AT₂R）在各组小鼠肺组织中的表达。结果：模型组小鼠血清AngⅡ含量较对照组增高（P<0.05）,坎地沙坦组与模型组比较无明显变化（P>0.05）。各组小鼠血清中AngⅠ含量比较差异无统计学意义（P>0.05）。模型组小鼠AT1R和ACE蛋白表达较对照组明显增加（P<0.05）,坎地沙坦组AT₁R表达与模型组比较明显降低(P<0.05),ACE无明显变化（P>0.05）。AT₂R蛋白表达各组间比较差异无统计学意义（P>0.05）。模型组小鼠ACE mRNA表达较对照组明显增加（P<0.05）,坎地沙坦组与模型组比较差异无统计学意义（P>0.05）。模型组小鼠AT1R mRNA表达较对照组明显增加（P<0.05）,坎地沙坦组较模型组明显降低（P<0.05）。模型组AT2R mRNA较对照组明显降低（P<0.05）,坎地沙坦组较模型组明显增加（P<0.05）。各组AGT mRNA表达无明显变化（P>0.05）。  结论：在小鼠哮喘发病过程中,RAS活化参与了哮喘的发病过程,并且AT₁R拮抗剂坎地沙坦可以逆转ACE、AT₁R和AT₂R表达的改变。     

AT1受体在同型半胱氨酸致动脉粥样硬化斑块不稳定性中的作用机制研究*

目的 探究血管紧张素Ⅱ1型受体（AT1）在同型半胱氨酸（Hcy）导致动脉粥样硬化斑块不稳定性中的作用。方法 将21只6周龄雄性载脂蛋白基因敲除小鼠随机分为对照组（CTL组）、高同型半胱氨酸组（HHcy组）和高同型半胱氨酸+替米沙坦组（HHcy+TLM组）,每组7只,共饲养12周。治疗前后测量各组体重、收缩压（SBP）。饲养12周后,摘眼球取血,检测血脂和Hcy。油红O染色主动脉根部斑块;免疫组织化学SP法检测斑块内炎症因子白细胞介素-6（IL-6）、单核细胞驱化蛋白-1（MCP-1）、巨噬细胞表面分子（mac-3）、基质金属蛋白酶-9（MMP-9）的表达水平;Masson染色胶原蛋白。结果 HHcy组的主动脉根部斑块面积大于CTL组（P?<0.05）,IL-6、MCP-1、MMP-9、mac-3的表达水平高于CTL组（P?<0.05）,而胶原含量低于CTL组（P?<0.05）;HHcy+TLM组斑块面积小于HHcy组,IL-6、MCP-1、MMP-9、mac-3的表达水平低于HHcy组,胶原含量高于HHcy组（P?<0.05）;HHcy+TLM组的SBP及体重与HHcy组比较,差异有统计学意义（P?<0.05）,HHcy+TLM组降低。结论 Hcy可促进动脉粥样硬化斑块发展且影响斑块的稳定性,而替米沙坦有逆转Hcy的作用,其机制可能是通过AT1受体实现的。     

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     

表皮生长因子受体及其信号转导通路与中西药肿瘤靶向治疗

表皮生长因子受体(epidermal growth factor receptor,EGFR)属于Ⅰ型受体酪氨酸激酶(receptor tyrosine kinase,RTK),是原癌基因ErbB1(HER1)的表达产物.EGFR广泛分布于哺乳动物的上皮细胞膜上,其信号可介导细胞的生长、增殖、分化、黏附、移动等生命现象[1,2].研究表明,包括非小细胞肺癌(non-small cell lung cancer,NSCLC)、乳腺癌、卵巢癌、胃癌、头颈癌、前列腺癌、膀胱癌、结肠癌等在内的多数肿瘤上皮可高表达EGFR,常与肿瘤进展、血管生成、转移扩散、凋亡受抑、放化疗抵抗密切相关.EGFR已成为肿瘤治疗的重要靶点[3].     

炎症积水的输卵管上皮组织中Toll样受体及信号转导通路的表达

目的 分析炎症积水的输卵管上皮组织中Toll样受体（TLR）基因和关键信号转导分子的表达格局.方法 根据沙眼衣原体IgG检测（CAT）结果,将输卵管炎症积水患者分为CAT阳性组（n=20）和CAT阴性组（n=8）;另设正常对照组（n=13）.运用实时定量PCR方法.分析输卵管上皮组织中TLR1～10及NF-KB、MyD88、TRAF、IRAK mRNA的表达.结果 CAT阳性组和阴性组TLR2 mRNA表达均显著低于对照组（P〈0.001）;而CAT阳性组与阴性组比较,差异无统计学意义（P〉0.05）.CAT阳性组TLR4 mRNA表达显著低于对照组（P〈0.001）和CAT阴性组（P〈0.05）;而CAT阴性组与对照组比较,差异无统计学意义（P〉0.05）.对照组MyD88 mRNA表达明显高于CAT阳性组（P〈0.01）和CAT阴性组（P〈0.05）;而CAT阳性组与阴性组比较,差异无统计学意义（P〉0.05）.结论 输卵管炎症积水可能与既往输卵管感染后机体自身免疫损伤及感染局部TLR2、4介导的免疫反应不足有关.     

RNA干扰特异性阻断胰岛局部血管紧张素II 1型受体对第一相胰岛素分泌的影响

目的：观察RNA干扰技术阻断胰岛局部血管紧张素II 1型受体（AT1R）表达后db/db小鼠胰岛第一相胰岛素分泌的变化并探讨其潜在机制。方法分离db/db和db/m小鼠的胰岛并检测AT1R mRNA和蛋白的表达。构建针对小鼠AT1R基因的RNA干扰重组腺病毒（Ad-siAT1R）及含对照序列的重组腺病毒（Ad-siControl）。将分离培养的db/db小鼠胰岛细胞分为三组：Ad-siAT1R感染组、Ad-siControl感染组、空白对照组。腺病毒感染后继续培养胰岛细胞72 h。检测各组AT1R、GLUT-2及葡萄糖激酶（GCK）的表达,并用胰岛灌流系统检测胰岛素动态分泌。结果 db/db小鼠胰岛中AT1R mRNA和蛋白表达水平比db/m小鼠胰岛高2倍左右（P<0.05）。腺病毒感染后,Ad-siAT1R组较Ad-siControl组胰岛AT1R mRNA表达水平下降75%,蛋白表达水平下降65%,而GLUT-2及GCK表达水平分别升高190%、121%（均P<0.05）。胰岛灌流显示：空白对照组和Ad-siControl组小鼠的胰岛素第一相分泌显著下降,仅为基础水平的1.8倍;而Ad-siAT1R组在高糖负荷后1~2 min即达到最高峰值140 mU/L,为基础水平的2.8倍,表明第一相胰岛素分泌明显改善。结论 RNA干扰特异性阻断胰岛局部AT1R表达可上调GLUT-2及GCK表达,恢复第一相胰岛素分泌,这可能是AT1R阻滞剂改善胰岛分泌功能的机制之一。     

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.     

血管紧张素Ⅱ受体拮抗剂减低大鼠体内脂肪

目的:探讨血管紧张素Ⅱ受体拮抗剂-Candesratan对大鼠脂肪细胞形态和功能的影响。方法:20只雄性W istarKyoto大鼠分为治疗组和对照组,分别予以口服Candesartan(10 mg.kg-1.d-1)和安慰剂,每周监测摄食量和体重变化。17周后处死大鼠,收集附睾和肾周围脂肪组织并称重;同时分离附睾脂肪细胞,测量细胞直径,抽提并测定脂肪组织甘油三酯;测定血浆生化、胰岛素、瘦素和脂联素;通过RT-PCR测定附睾脂肪瘦素、脂联素和前脂肪细胞因子-1mRNA基因表达。结果:Candesartan治疗组大鼠体重和体内脂肪含量较对照组明显减低,附睾脂肪细胞缩小,细胞构成升高,但总细胞数无明显表化;两组间血糖和胰岛素无显著差异,治疗组血瘦素水平和脂肪组织瘦素mRNA表达均降低,而血脂联素水平升高、脂肪组织脂联素mRNA表达增加,前脂肪细胞因子-1mRNA表达则无变化。结论:血管紧张素Ⅱ受体拮抗剂使脂肪细胞缩小,从而减少脂肪组织含量,同时增加脂联素的合成和分泌。     

炎症积水的输卵管上皮组织中Toll样受体及信号转导通路的表达

目的 分析炎症积水的输卵管上皮组织中Toll样受体(TLR)基因和关键信号转导分子的表达格局.方法 根据沙眼衣原体IgG检测(CAT)结果,将输卵管炎症积水患者分为CAT阳性组(n=20)和CAT阴性组(n=8);另设正常对照组(n=13).运用实时定量PCR方法.分析输卵管上皮组织中TLR1～10及NF-KB、MyD88、TRAF、IRAK mRNA的表达.结果 CAT阳性组和阴性组TLR2 mRNA表达均显著低于对照组(P<0.001);而CAT阳性组与阴性组比较,差异无统计学意义(P>0.05).CAT阳性组TLR4 mRNA表达显著低于对照组(P<0.001)和CAT阴性组(P<0.05);而CAT阴性组与对照组比较,差异无统计学意义(P>0.05).对照组MyD88 mRNA表达明显高于CAT阳性组(P<0.01)和CAT阴性组(P<0.05);而CAT阳性组与阴性组比较,差异无统计学意义(P>0.05).结论 输卵管炎症积水可能与既往输卵管感染后机体自身免疫损伤及感染局部TLR2、4介导的免疫反应不足有关.     

糖尿病大鼠脑内血管紧张素Ⅱ含量及其1型受体表达的变化

目的了解糖尿病（diabetes mellitus，DM）大鼠脑内血管紧张素Ⅱ（AngⅡ）含量及其1型受体（ATD表达的改变。方法以链脲佐菌素（STZ）诱导的DM大鼠为研究对象。采用免疫组化观测大鼠脑内AT1的表达；用放射免疫分析法测定血浆及脑组织AngⅡ的含量。结果DM发生14天后，血浆和下丘脑的AngⅡ含量升高，延髓AngⅡ含量降低，视上核（SON）、室旁核（PVN）、孤束核（NST）的AT1表达显著增强，而穹隆下器官（SFO）的AT1表达则显著减弱。结论DM大鼠的中枢和血浆的AngⅡ含量及AT1在脑内的表达有异常改变。     

血管紧张素转化酶2/血管紧张素（1⁃7）信号轴与新型冠状病毒肺炎的关系探究

血管紧张素转换酶 2（angiotensin?converting enzyme 2,ACE2）是人体肾素?血管紧张素系统（renin?angiotensin system,RAS）的一个重要成员,其生理作用主要是催化血管紧张素（angiotensin,Ang）Ⅱ转换为Ang?（1?7）。新型冠状病毒的暴发和快速的传播能力,使其成为全世界共同关注的重大突发公共卫生事件。新型冠状病毒通过与人体黏膜上皮细胞膜表面的ACE2结合入侵细胞,并且大量复制,产生肺炎。其传染性强,目前无确切有效的治疗方式。高血压是新型冠状病毒肺炎最常见的合并症。新型冠状病毒肺炎患者体内ACE/Ang Ⅱ/AT1R轴和ACE2/Ang?（1?7）/Mas轴失衡,本课题组既往对Ang?（1?7）的系列研究和其他实验室的研究结果显示,Ang?（1?7）具有保护心肺功能、舒张血管、降低血压、上调ACE2表达的作用。外源性给予Ang?（1?7）不仅可以缓解和扭转人体自身的RAS失衡,还可以对肺部、心血管等系统起到支持和保护作用。因此Ang?（1?7）具有治疗或缓解新型冠状病毒肺炎合并高血压的潜在可能。     

Angiotensin Ⅱ induced upregulation of Gαq/11, phospholipase Cβ3 and extracellular signal-regulated kinase 1/2 via angiotensin Ⅱtype 1 receptor

Background The role of the Gαq/11-mediated signal transduction pathway in angiotensin Ⅱ (Ang Ⅱ) induced cardiac hypertrophy remains unclear. This study was to investigate the role of the Gαq/11 signal transduction pathway in the development of cardiac hypertrophy in 2K1C hypertensive rats and in cultured neonatal rat ventricular myocytes (NRVMs) and to elucidate the effects of the pathway on Ang Ⅱ induced cardiac hypertrophy.Methods Renal hypertension was induced in 2K1C hypertensive rats by placing a silver clip around the left renal artery. At 8 weeks after operation, the systolic blood pressure, the ratio of left ventricular weight to body weight (LV/BW), and the concentration of AngⅡ in the heart were measured. The protein levels of Gαq/11 and extracellular signal-regulated kinase 1/2 (ERK1/2) were assayed by Western blot analysis, and the activity of phospholipase C (PLC) in the myocardium was detected using ［3H］-PIP2 as a substrate. Changes in ［3H］-leucine incorporation and in the protein levels of the signal molecules Gαq/11, PLCβ3, and ERK1/2 were measured after NRVMs were stimulated with 10-7mol/L AngⅡ.Results The protein levels of Gαq/11 and ERK1/2 in the hearts of 2K1C rats increased by 35.8% and 31.9%, respectively, compared with the sham group. The PLC activity in the 2K1C group was also significantly increased (P&lt;0.05). The levels of Gαq/11, PLCβ3, and ERK1/2 increased significantly after NRVMs were stimulated by AngⅡ. The upregulation of Gαq/11, PLCβ3 and ERK1/2 in NRVMs occurred prior to ［3H］-leucine incorporation increases, and could be inhibited with losartan. Conclusion AngⅡ can initiate cardiac hypertrophy and upregulate signal molecules in the Gαq/11-mediated signal transduction pathway, such as Gαq/11, PLCβ3 and ERK1/2, at both tissue and cellular levels.     

AT1和AT2在室间隔缺损并肺动脉高压肺小血管壁上的表达及意义

目的: 研究血管紧张素Ⅱ受体AT1和AT2在先天性心脏病室间隔缺损合并不同程度肺动脉高压的组别间肺小血管壁上的表达及其与肺动脉高压相关性.方法: 应用AT1及AT2的特异性多克隆抗体结合、免疫组化ElivisionTM plus法染色、灰度分析.结果: 肺小动脉AT1和AT2的灰度值在多组间有显著性差异(P<0.01);各组间肺小动脉AT1和AT2灰度值分别比较均有显著性差异(P<0.01);AT1和AT2在肺小静脉的灰度值在多组间无统计学差异(P>0.05);AT1和AT2在肺小动脉的灰度值与肺动脉压力呈正相关(相关系数分别为r=0.954和r＝0.826).结论: AT1和AT2可能与肺动脉高压的发展有关.