Urotensin II induces transactivation of the epidermal growth factor receptor via transient oxidation of SHP-2 in the rat renal tubular cell line NRK-52E

Urotensin-II (UII) is a potent vasoactive peptide that has been implicated in cardiac fibrosis and renal diseases. However, the role played by UII in renal tissues is largely unknown. In this study, we investigated the effects of human UII (hUII) on rat renal proximal tubular cells of the NRK-52E line and the role of Src homology 2-containing phosphotyrosine phosphatase (SHP-2) in the hUII-induced transactivation of the epidermal growth factor receptor (EGFR). Exposure to hUII at low concentrations significantly induced proliferation in NRK-52E cells; this effect was inhibited by treatment with an ERK1/2 inhibitor (PD98059). UII treatment increased the phosphorylation of EGFR and induced the generation of reactive oxygen species (ROS). Treatment of the ROS scavenger N-acetyl-cysteine (NAC) inhibited EGFR transactivation and ERK phosphorylation induced by hUII. SHP-2 was found to interact with EGFR and be transiently oxidized following the hUII treatment. In SHP-2 knockdown cells, UII-induced phosphorylation of EGFR was less influenced by NAC, and significantly suppressed by heparin binding (HB)-EGF neutralizing antibody. Our data suggest that the ROS-mediated oxidation of SHP-2 is essential for the hUII-induced mitogenic pathway in NRK-52E cells.     

慢性栓塞性肺动脉高压大鼠肺动脉重塑与尾加压素Ⅱ及其受体的表达

目的 研究尾加压素Ⅱ(U Ⅱ)蛋白和mRNA及U Ⅱ受体(UT)mRNA在慢性栓塞性肺动脉高压大鼠肺动脉的表达,探讨其在病程中的作用.方法 雄性Wistar大鼠,麻醉后经颈静脉注入体外制备的血栓栓子,2周后同法进行2次栓塞,造模成功大鼠分为2周组、4周组、8周组、12周组,全程腹腔注射抗纤维溶解剂氨甲环酸,达到目标日期后行以下检查:(1)测量平均肺动脉压(mPAP);(2)用免疫学检验和原位杂交的方法检测不同节段肺动脉U Ⅱ蛋白和mRNA表达及UT mRNA表达;(3)在光镜下观察肺动脉显微结构的变化,测定肺动脉相对中膜厚度(PAMT)和管壁面积/管总面积(WA/TA).采用SPSS 13.0软件,所有数据以-x±s表示,组间比较采用单因素方差分析,组间差异采用LSD方差分析.结果 (1)栓塞后4、8及12周组的大鼠mPAP值分别为(19.9±6.2)mm Hg(1 mm Hg=0.133 kPa)、(23.8±4.1)mm Hg、(27.4±5.4)mm Hg,较对照组明显升高(F值为13.75,P＜0.01),PAMT百分比分别为42.6±11.16、47.82±10.02、53.79±10.41,WA/TA百分比分别为22.75±6.79、25.32±4.90、27.05±7.71,较对照组均明显增大(F值分别为5.52和6.61,P均＜0.01);(2)栓塞后肺动脉U Ⅱ蛋白和U Ⅱ mRNA以及UT mRNA表达上调,细小动脉较中型动脉变化更为明显,4、8及12周组肺细小动脉U Ⅱ mRNA和UT mRNA及U Ⅱ蛋白平均吸光度值分别为0.138±0.019、0.144±0.022、0.173±0.021和0.126±0.028、0.146±0.029、0.157±0.025,与对照组相比明显升高(F值分别为30.39、30.78和14.49,P均＜0.01),随着栓塞时间的延长,表达呈明显增加的趋势;(3)肺细小动脉U Ⅱ蛋白和mRNA及UT mRNA的平均吸光度值均与mPAP、PAMT呈正相关关系(r值分别为0.822、0.866、0.846;0.675、0.712、0.756,P均＜0.01).结论 慢性栓塞性肺动脉高压大鼠出现明显肺动脉重构,尾加压素Ⅱ蛋白和mRNA及其UT mRNA在肺动脉表达明显上调,其动态变化与肺动脉高压、肺血管重构的病理过程明显相关.     

Urotensin II in patients with chronic heart failure

BACKGROUND: Human Urotensin II (hU-II) is the most potent vasoconstrictor known to date. HU-II receptors are predominant in the human heart and arterial vessels, suggesting hU-II to be of importance as a cardiovascular mediator. METHODS: We studied 32 consecutive patients (60+/-12 years) with chronic heart failure (CHF) and 10 control subjects (54+/-12 years, n.s.) with cardiopulmonary exercise testing. Blood samples for the measurement of plasma hU-II and big-endothelin-1 (big-ET1) were obtained at rest and at peak exercise. RESULTS: Peak VO(2) was significantly higher in controls than in CHF patients (19.8+/-3.8 vs. 14.7+/-3.6 ml min(-1) kg(-1), P<0.001). Big-ET1 levels were increased in CHF compared to controls at rest (2.8+/-1.8 vs. 1.7+/-0.1 fmol/ml, P<0.01) and at peak exercise (2.7+/-1.7 vs. 1.6+/-0.2 fmol/ml, P<0.005). HU-II concentrations were comparable in patients with CHF and controls at rest (2990+/-1104 vs. 3290+/-508 pg/ml, n.s.) and peak exercise (3063+/-1185 vs. 3213+/-1188 pg/ml, n.s.). Resting hU-II levels demonstrated no correlation with peak VO(2) in controls or CHF patients. CONCLUSIONS: The measurement of circulating plasma levels of hU-II does not seem to be very helpful in studying the effects of hU-II in human cardiovascular regulation. A local paracrine or autocrine mediator effect of hU-II in CHF is possible.     

尾加压素Ⅱ促血管内皮细胞分泌肾上腺髓质素的作用

目的研究人尾加压素（human urotensinⅡ,HUⅡ）对人血管内皮细胞（human vascular endothelial cells,HVEC）分泌肾上腺髓质素（adrenomedullin,ADM）的影响及可能机制。方法不同浓度的HUⅡ（10^-10～10^-7mol／L）刺激培养的HVEC,用放射免疫法测定其分泌ADM的量,并加入不同细胞信号转导分子阻滞剂以测定其对分泌的影响。结果HUⅡ呈时间和浓度依赖性的增加HVEC分泌ADM。细胞外信号调节激酶抑制剂PD98059及钙调素依赖性蛋白激酶抑制剂W7、P38蛋白激酶抑制剂SB202190及钙通道阻滞剂nicardipine均能抑制HUⅡ刺激的HVEC对ADM的分泌,其抑制率分别为68％（P〈0．01）、78％（P〈0．01）及24％（P〈0．05）、25％（P〈0．05）;蛋白激酶C抑制剂H7、钙调神经磷酸酶抑制剂环孢霉素（CsA）对HUⅡ刺激HVEC分泌ADM无明显影响。结论HUⅡ能刺激HVEC分泌ADM,其作用可能与Ca^2＋、ERKs、CaM PK及P38介导的信号转导通路有关。     

尾加压素Ⅱ与中介素在急性呼吸窘迫综合征中的作用初探

尾加压素Ⅱ最早是从硬骨鱼尾部神经分泌细胞中分离出的环肽,尾加压素Ⅱ受体激活后,通过多种信号传导途径,引起增强心肌收缩、血管收缩、扩张等一系列心血管效应,是迄今已知体内最强的缩血管活性肽。中介素是一种新型血管活性肽,属降钙素基因相关肽家族成员,具有介导心肌收缩,血管舒张,调节细胞增殖、肥大、迁移、凋亡等多种生物学效应,该...     

Urotensin II: lessons from comparative studies for general endocrinology

The importance of combining studies across vertebrates to provide insights into the functionality of hormone systems is considered, using recent advances in Urotensin II (UII) biology to illustrate this. The impact of genome analyses on understanding ligand and UII receptor (UT) structures is reviewed, noting their high conservation from fish to mammals. The early linkage of UII with fish osmoregulatory physiology drove our investigation of possible renal actions of UII in mammals. The kidney is a potential major source of UII in mammals and endogenous peptide appears to have tonal influence over renal excretion of water and electrolytes. Blockade of UII actions by administration of UT receptor antagonist, urantide, in anaesthetised rats, indicates that endogenous UII lowers renal filtration rates and excretion of water and ions. These effects are considered in relation to apparent association of UII with a number of human cardiovascular and renal disorders. Following up the sequencing of UT in mammals here we contrast the first fish UT sequences with those in other species. It is now evident that UT expression in fish osmoregulatory tissues, such as the gill and kidney, exhibits considerable plasticity in response to physiological challenge, providing an important component of the adaptive organismal responses. A number of areas of UII research, which will continue to benefit from moving questions between appropriate vertebrate groups, have been highlighted. These comparative approaches will yield improved understanding and further novel actions of this intriguing endocrine and paracrine system, so highly conserved across the vertebrate series.     

黄芪对糖尿病肾病大鼠尾加压素Ⅱ表达的影响

目的探讨黄芪对糖尿病肾病大鼠表达的影响。方法采用高糖高脂饮食和链脲佐菌素（STZ）腹腔注射法建立大鼠糖尿病肾病模型。将大鼠分为正常对照组（NC,n=10）、糖尿病肾病组（DN,n=10）、黄芪治疗组（HZ,n=10）（予黄芪注射液5 ml/kg灌胃）。于14周末处死动物,进行以下实验：测定血糖（BG）、胆固醇（TC）、甘油三酯（TG）、高密度脂蛋白（HDL）、血肌酐（Scr）、尿素氮（BUN）和尿蛋白定量（24 h UTP）;免疫组织化学技术检测UⅡ蛋白表达,RT-PCR技术检测UⅡmRNA表达。结果与NC组相比,各模型组肾脏肥大指数（KI）、BG、TC、TG、Scr、BUN和24 h UTP明显升高,HDL明显降低,差异有统计学意义（P〈0.01）;HZ组的上述指标与DN组比较,则有明显降低,差异有统计学意义（P〈0.05）。与NC组比较,DN组肾组织UⅡ表达增加,UⅡmRNA表达增加（P〈0.01）;与DN组比较,HZ组肾组织UⅡ表达明显降低,UⅡmRNA表达显著减少（P〈0.05）。结论黄芪可治疗糖尿病肾病,其机制可能与降低肾组织UⅡ蛋白及其mRNA的过度表达有关。     

Urotensin I-CRF-Urocortins: A mermaid’s tail

From the individual perspective of the two authors who were long-time colleagues of Karl Lederis at the University of Calgary, the events and personal interactions are described, that are relevant to the discovery of Urotensin I (UI) in the Lederis laboratory, along with the concurrent discovery of Urotensin II (UII) in the Bern laboratory and corticotropin-releasing factor (CRF/CRH) in the Vale laboratory. The fortuitous sabbatical experiences that put Professors Lederis and Bern on the track of the Urotensins, along with the essential isolation paradigm that resulted in the complete sequencing and synthesis of UI and UII are summarized. The chance interaction between Drs. Vale and Lederis who, prior to the publications of the sequences of UI and CRF, realized the sequence commonalities of these peptides with the vasoactive frog peptide, sauvagine, is outlined. Further, the relationship between the pharmacological studies done with UI in the Calgary laboratory and the more recent understanding of the biology and receptor pharmacology for the entire Urotensin I-CRF-Urocortin peptide family is dealt with. The value of a comparative endocrinology approach to understanding hormone action is emphasized, along with a projection to the future, based on new hypotheses that can be generated by unexplained data already in the literature. Based on the previously described pharmacology of the UI-CRF-Urocortin peptides in a number of target tissues, it is suggested that the use of current molecular approaches can be integrated with a ‘classical’ pharmacological approach to generate new insights about the UI-CRF-Urocortin hormone family.