Role of Wnt signaling pathway on the epithelial to mesenchymal transition induced by parathyroid hormone in renal tubular epithelial cells

Objective To observe the effect of parathyroid hormone on transdifferentiation of human renal proximal tubular epithelial cell (HK-2), and to investigate the role of Wnt signaling pathway in this process. Methods The expression of α-SMA, E-cadherin mRNA and protein was detected by real-time PCR and Western blotting. After the induction of 10-10 mol/L PTH for 48 h, the Wnt pathway associated gene expression profiling was detected by quantitative PCR-microarray. The expression of Wnt4 mRNA and protein under various concentrations of PTH or after exposed to 10-10 mol/L PTH for different time was detected by real-time PCR and Western blotting. The overexpression and knock-down plasmids of Wnt4 were constructed and the expression of α-SMA, E-cadherin, Wnt4 mRNA and protein was detected by real-time PCR and western blotting after overexpression and knockdown of Wnt4. Results Compared with PTH group, the expression of α-SMA mRNA and protein in PTH+DKK1 group was significantly down-regulated, while E-cadherin mRNA and protein expression was significantly up-regulated (all P＜0.01). PTH treatment resulted in the up-regulation of 18 genes and down-regulation of 9 genes associated with Wnt pathway. Compared with control group, the expression of Wnt4 mRNA and protein increased markedly in PTH group (all P＜0.01). The expression of α-SMA mRNA and protein was significantly up-regulated and E-cadherin mRNA and protein expression was significantly down-regulated after overexpression of Wnt4 and PTH treatment (all P＜0.05), while the expression of α-SMA mRNA and protein was significantly down-regulted and E-cadherin mRNA and protein expression was significantly down-regulated after knockdown of Wnt4 and PTH treatment (all P＜0.05). Conclusions PTH-induced EMT in HK-2 cells is mediated by Wnt signal pathway, and Wnt4 might be a key gene during PTH-induced EMT.     

白细胞介素18对促进肾小管萎缩和间质纤维化的影响

目的:探讨白细胞介素18(IL-18)对肾小管萎缩和间质纤维化的作用.方法:在体外实验中应用不同浓度的IL-18处理人类近端肾小管上皮细胞株(HK-2).应用Hoechst 33258染色法检测细胞凋亡;应用流式细胞技术和免疫组化技术检测细胞表达α-平滑肌肌动蛋白(α-SMA)表达和细胞形态学的变化.结果:低浓度短时间 IL-18作用对细胞凋亡无影响,而较高浓度IL-18作用可促使肾小管上皮细胞凋亡;IL-18具有显著促进肾小管上皮细胞表达α-SMA作用,并呈剂量和时间依赖关系,而且表达α-SMA的细胞具有肌成纤维细胞的形态学特征.结论:肾病状态下IL-18可能具有促进肾小管萎缩和肾间质纤维化的作用.     

胰腺癌细胞起源和演进的新实验证据

目的大量研究证实导管样复合体就是胰腺癌的前体病变，因此，本研究旨在探索植入致癌剂后胰腺癌前体病变的产生和发展。方法采用手术方法将致癌剂DMBA植入SD大鼠胰腺，从第1天开始，在不同的时间点获取胰腺进行组织学研究，同时，分别以糜蛋白酶和细胞角蛋白作为胰腺腺泡细胞和导管细胞的标记物，通过免疫组化方法进行定位。结果在包埋致癌剂第2天就可以观察到正常胰腺小叶向导管复合体移型的现象，第4天出现典型的导管复合体，同时，胰岛也参与了这一过程。小叶中的非导管细胞迅速转分化为导管细胞的特征。在1个月时观察到导管腺癌的形成。与对照组相比，腺泡一导管转分化过程在DMBA包埋组持续存在。结论胰腺癌前体病变(导管复合体)除了由已经存在于小叶内的导管细胞组成外，主要通过腺泡细胞转分化形成，同时，胰岛细胞在某种程度上也参与了导管复合体的形成。因此，胰腺腺泡细胞、胰岛细胞和导管细胞共同参与了胰腺导管腺癌前体细胞的起源，转分化可以不需要细胞分裂迅速发生，而恶性转化需要较长的时间。     

Pathophysiological Characteristics of Dimethylnitrosamine-Induced Liver Fibrosis in Acute and Chronic Injury Models: A Possible Contribution of KLF5 to Fibrogenic Responses

Dimethylnitrosamine administration induces a rapid increase in collagen deposition with concomitant proliferation of hepatic stellate cells in rats. Here, we investigated the pathophysiological profiles of acute and chronic hepatic fibrosis states and attempted to determine the possible role of Kruppel-like factor-5 (KLF5) in this model. In acute study using a single drug injection, we observed a rapid transient increase of ALT and mRNA levels of KLF5 followed by increases in fibrosis-related genes. Repeated administration of dimethylnitrosamine once a week caused early damage with severe fibrosis and sustained hepatocyte injury, while intermittent injections at 2-week intervals induced only modest fibrosis from 3 weeks. Weekly administration also induced profound upregulation of collagen I, alpha-smooth muscle actin, and KLF5 mRNA. In contrast, such continued augmentation was not observed after intermittent injections; KLF5 increased only after 3 weeks. These results suggested that dimethylnitrosamine induced a rapid hepatic fibrogenic response with a possible participation of KLF5.     

汉防己甲素对马兜铃酸A诱导的人近端肾小管上皮细胞转分化的干预作用

目的：探讨汉防己甲素（tetrandrine,rret）对马兜铃酸A（aristoloehic acid Ⅰ,AAⅠ）诱导的人近端肾小管上皮细胞（HK-2）转分化的拮抗效应。方法：将正常培养的HK-2随机分组：正常组、模型组、汉防己甲素高浓度组、汉防己甲素中浓度组、汉防己甲素低浓度组、泼尼松龙对照组（糖皮质激素组）。48h后观察各组细胞形态的变化,逆转录-聚合酶链式反应方法检测各组E—cadherin、TGF-β1、α-SMA mRNA表达水平,双抗体夹心酶联免疫吸附法测定各组细胞培养液中TGF-β1浓度,流式细胞技术测定各组E—cadherin阳性表达细胞的百分率。结果：汉防己甲素干预组及泼尼松龙对照组E—cadherin mRNA表达水平明显高于模型组（P〈0．05）,相反,其TGF-β1、α-SMA mRNA表达水平明显低于模型组（P〈0．05）;汉防己甲素干预组及泼尼松龙对照组TGF-β1浓度亦明显低于模型组（P〈0．05）;汉防己甲素干预组（中、低浓度）E—cadherin阳性表达细胞的百分率明显高于模型组（P〈0．05）,但汉防己甲素高浓度组和泼尼松龙对照组E—cadherin阳性表达细胞的百分率较之模型组增高不明显（P〉0．05）。结论：一定浓度（10μg／ml）的AAⅠ能诱导体外培养的HK-2转分化,适当浓度的Tet对AAi诱导的HK-2转分化具有明显的拮抗作用;AAI亦能上调TGF-β1的表达,而适当浓度的Tet能拮抗AAI引起的TGF-β1的高表达。     

细胞转分化检测技术及应用

细胞究竟发生了转分化还是发生了融合,曾经倍受争议。随着检测手段的进步,转分化正逐渐被人们认同。在细胞转分化的研究中,有关转分化的检测技术至关重要。本文就目前其主要检测技术及相关内容作一综述。     

胚胎分化/发育基因pax2与WT1的序列启动在肾小管上皮细胞逆向分化中的意义

目的： 通过观察肾小管上皮细胞(TEC)胚胎分化/发育关键基因Wilm’s肿瘤基因（WT1）和pax2的序列启动，探讨TEC逆向分化的分子机制及病理生理学意义。方法：从胚胎肾、肾脏损伤模型及体外细胞培养3方面入手，通过RT-PCR、免疫组织化学等技术，研究TEC逆向分化时，胚胎期控制TEC分化/发育的关键基因pax2和WT1的表达、pax2和WT1之间的关系以及它们与TEC逆向分化间的关系。结果：（1）胚胎期：pax2和WT1 mRNA先后在胚胎11.5 d及14 d时开始出现表达并逐渐增强，出生14 d后仅有痕量表达。免疫组化显示，成年大鼠中仅肾小球足突细胞表达WT1，TEC中pax2和WT1表达阴性。（2）5/6慢性肾损伤模型：损伤第2周，部分TEC重新出现pax2和WT1的表达，第4周达高峰，两者表达趋势相吻合。pax2在第10周尚有一个新的表达高峰，随后逐渐下降至痕量。（3）TEC体外培养：经炎性因子IL-1α(10 μg/L)、AngII（10-9 mol/L）掺入培养后，TEC分别在0.5、24 h内重新表达pax2 和WT1，随后α-SMA出现高表达，细胞呈现间充质样细胞特征。以WT1中和抗体、AngII 受体阻断剂封闭WT1和pax2基因的作用后，α-SMA表达水平明显降低，细胞基本保持原有特征不变。结论：控制胚胎肾分化/发育的关键基因pax2和WT1在成年肾遭受损伤时，可获得重新表达，呈现序列启动现象，TEC同时出现胚胎间充质细胞特征；pax2和WT1的重新表达与细胞浸浴环境（高浓度细胞因子）密切相关，可能作为内在启动机制参与TEC的逆向分化。     

N-乙酰半胱氨酸对TGF-β1诱导的ARPE-19细胞向肌成纤维细胞转分化的影响

背景 视网膜色素上皮(RPE)细胞转分化为肌成纤维细胞是增生性玻璃体视网膜病变发生和发展中的一个核心事件.N-乙酰半胱氨酸(NAC)能够通过抑制转化生长因子-β1(TGF-β1)诱导的细胞内活性氧(ROS)的产生和MAPK蛋白的磷酸化来抑制多种细胞向肌成纤维细胞的转分化,但是NAC对TGF-β1诱导的人RPE细胞系ARPE-19细胞向肌成纤维细胞转分化的影响及其潜在的分子机制尚不清楚. 目的 研究NAC对TGF-β1诱导的ARPE-19细胞向肌成纤维细胞转分化的影响及其潜在的分子机制.方法 体外培养人ARPE-19细胞并分为对照组、TGF-β1处理组、NAC干预组和NAC单独处理组,对照组不做处理,其他3个组分别使用10 ng/ml TGF-β1、10 ng/ml TGF-β1 +5 mmol/L NAC和5 mmol/L NAC处理细胞48 h,相差显微镜下观察细胞的形态学改变.采用实时荧光定量PCR、Western blot、免疫荧光及ELISA法检测转分化标志基因α-平滑肌肌动蛋白(α-SMA)、纤维结合蛋白及Ⅰ型胶原的表达情况.使用非荧光探针DCFH-DA通过流式细胞仪检测在TGF-β1处理后1h,细胞内ROS的产生情况及NAC对细胞内ROS产生的影响.采用Western blot法检测各组细胞内p38MAPK、ERK1/2及SAPK/JNK蛋白磷酸化的影响.采用细胞计数试剂盒-8(CCK-8)法检测不同浓度NAC对ARPE-19细胞生存的影响. 结果 实时荧光定量PCR、Western blot及ELISA实验结果表明,与对照组相比,TGF-β1处理组α-SMA、纤维结合蛋白和Ⅰ型胶原mRNA表达水平均上调,分别是对照组的(2.15±0.29)、(9.54±1.08)和(25.78±0.66)倍,蛋白表达水平分别是对照组的(8.49±0.32)、(2.53±0.69)和(4.45±1.05)倍,差异均有统计学意义(均P＜0.05).NAC干预组α-SMA、纤维结合蛋白和Ⅰ型胶原mRNA的表达水平分别是TGF-β1处理组的(66.70±12.57)％、(66.11±8.35)％和(33.19±6.90)％,蛋白表达水平分别是TGF-β1处理组的(52.30±4.83)％、(55.03±2.58)％和(56.08±3.65)％,差异均有统计学意义(均P＜0.05).流式细胞仪分析结果显示,TGF-β1处理组细胞内ROS的产生水平较对照组增加,是对照组的(2.12±0.20)倍,NAC干预组细胞内ROS水平是TGF-β1处理组的(57.41±9.45)％,差异均有统计学意义(均P＜0.01).Western blot结果显示,与对照组相比,TGF-β1处理组p38MAPK、SAPK/JNK及ERK1/2蛋白磷酸化水平均上调,分别是对照组的(9.18±1.00)、(4.87±0.81)和(4.20±0.69)倍,差异均有统计学意义(均P＜0.05).使用NAC干预处理后,p38MAPK、SAPK/JNK及ERK1/2蛋白磷酸化水平分别是TGF-β1处理组的(48.16±14.82)％、(67.90±2.90)％和(74.52±4.00)％,差异均有统计学意义(均P＜0.05). 结论 NAC可能通过抑制TGF-β1诱导的ROS的产生及p38MAPK、SAPK/JNK及ERK1/2蛋白的磷酸化进而抑制ARPE-19细胞向肌成纤维细胞转分化.     

Haematopoietic stem cells improve cardiac function after infarction without permanent cardiac engraftment

BACKGROUND: Transplantation of bone marrow derived adult stem cells (BMC) improves cardiac function after acute myocardial infarction (MI). However, the cell population mediating myocardial recovery and the fate of the transplanted cells are still controversial. AIMS: We determined the effects of Sca-1+ c-kit+ lin- haematopoietic BMC on cardiac function after MI and the cell fate after transplantation. METHODS: Sca-1+ c-kit+ lin- BMC of male donor C57BL/6 mice were transplanted by intravenous injection into syngenic females after permanent MI. LV dimensions and function were determined by echocardiography and cardiac magnetic resonance imaging, transplanted BMC were identified by Y chromosome DNA in situ hybridization. RESULTS: BMC treatment completely prevented LV dilation (LV end-diastolic volume BMC 70 +/- 16 microl vs. control 122 +/- 41 microl; p < 0.05) and improved fractional shortening (BMC 22.9 +/- 8% vs. control 15.4 +/- 8.4%; p < 0.05) and ejection fraction BMC 68.2 +/- 6.6% vs. control 52 +/- 14.3%; p < 0.05) as early as 3 days after transplantation, but did not decrease infarct size (BMC 27 +/- 6% vs. control 28 +/- 7%, p = n.s.). After 4 weeks, only sporadic cells of male origin were identified in infarcted hearts (< 0.01% of periinfarct cells). CONCLUSION: Intravenous injection of Sca-1+ c-kit+ lin- in BMC after MI improves LV dimensions and function without evidence for long term engraftment.     

氯沙坦对梗阻性肾病大鼠肾间质固有细胞的作用

目的研究氯沙坦对梗阻性肾病大鼠肾间质固有细胞的作用,寻找可能的临床抑制肾间质纤维化的方法。方法采用单侧输尿管结扎(UUO)模型,治疗组于造模当日至造模后14天给予科素亚[16mg(kg·d)]灌胃,另设假手术组及手术组作为对照。应用免疫组织化学方法检测肾间质TGF-β的表达,组化双染色观察α-SMA、E-钙粘素的表达。激光共聚焦显微镜观察间质小管区α-SMA表达。结果手术组两周时出现近端肾小管区TGF-β表达明显增高(P<0．01),伴α-SMA表达增高(P<0．01),E-钙粘素表达下降(P<0．05),部分肾小管细胞中可见α-SMA及E-钙粘素同时表达;治疗组与手术组相比TGF-β、α-SMA的表达明显下降(P<0．05),而E-钙粘素的表达上调(P<0．05)。共聚焦显微镜下见部分小管基底膜损伤,上皮细胞表达α-SMA。结论氯沙坦可通过抑制肾间质固有细胞转分化过程的进展,从而对肾间质纤维化具有治疗作用。