肾间质纤维化中DJ-1抑制抗纤维化因子PTEN的表达

目的 观察肾小管上皮细胞转分化过程中PTEN的表达和分布,并研究上调DJ-1 对 PTEN 表达和分布及 PI3K-Akt 通路活化的影响。 方法 以人肾小管上皮细胞为研究对象,10 μg/L TGF-β1 刺激72 h 诱导人肾小管上皮细胞转分化;Western印迹法检测正常组和 TGF-β1 干预组细胞内 PTEN、E-cadherin 和α-SMA 蛋白表达;RT-PCR 法检测两组细胞内 PTEN mRNA 表达水平。脂质体法介导 pEGFP-N1-DJ-1 或空载体转染人肾小管上皮细胞,倒置荧光显微镜和Western印迹鉴定转染效率后,Western印迹法检测正常组、pEGFP-N1-DJ-1 转染组和空载体转染组细胞内 PTEN 蛋白表达;RT-PCR 法检测各组细胞内 PTEN mRNA 表达。pEGFP-N1-DJ-1 转染前 1 h 用 PI3K 抑制剂 LY294002 预处理,Western印迹检测正常组、pEGFP-N1-DJ-1 转染组和空载体转染组及 LY294002 预处理1 h 后 pEGFP-N1-DJ-1 转染组的 p-Akt 和Akt蛋白的表达。激光共聚焦显微镜下观察正常组、TGF-β1 干预组和 pEGFP-N1-DJ-1 转染组细胞内 PTEN 蛋白的分布。 结果 正常组细胞表达 E-cadherin 和 PTEN,几乎不表达α-SMA;TGF-β1干预组α-SMA 表达显著高于正常组（P < 0.05）,而 E-cadherin表达显著低于正常组（P < 0.05）,PTEN mRNA 和蛋白表达均显著低于正常组（P < 0.05）。pEGFP-N1-DJ-1和空载体转染后,细胞绿色荧光表达均在 80% 以上;pEGFP-N1-DJ-1 转染组细胞内 DJ-1 表达显著高于正常组（P < 0.05）,而 PTEN mRNA 和蛋白表达均显著低于正常组（P < 0.05）;pEGFP-N1-DJ-1 转染组p-Akt 表达显著高于正常组（P < 0.05）,但经 LY294002 干预后与正常组表达基本一致。正常组细胞内PTEN 分布于细胞质和细胞核;TGF-β1 干预组细胞质内 PTEN 几乎完全消失,而细胞核PTEN 略有增加;pEGFP-N1-DJ-1 转染组细胞核表达PTEN,但细胞质几乎无 PTEN 表达,这与 TGF-β1干预组相似。 结论 肾间质纤维化中高表达 DJ-1 可抑制 PTEN 表达,并促进 PI3K-Akt 通路活化。     

高糖通过转化生长因子β1-Smad信号传递途径诱导肾小管上皮细胞转分化

目的 通过观察高糖对肾小管上皮细胞转分化(EMT)的作用，探讨其与转化生长因子β1 (TGF-β1)的关系及糖尿病肾病肾小管间质纤维化的发病机制。 方法 以人肾小管上皮细胞株HKC细胞和高表达Smad7蛋白的HKC转染细胞株为研究对象。蛋白印迹法检测高糖(葡萄糖浓度分别为25和50 mmol/L)对α平滑肌肌动蛋白(α-SMA)、E钙黏蛋白 (E-cadherin)和纤连蛋白(FN)表达的影响。酶联免疫吸附(ELISA)法检测TGF-β1的水平。Boyden小室检测HKC细胞的迁移能力。抗TGF-β1抗体中和实验分析高糖对肾小管EMT作用及与TGF-β1的关系。 结果 持续的高糖作用(96 h)能够导致HKC表达α-SMA蛋白，其中25和50 mmol/L的葡萄糖分别增加表达α-SMA 2.8倍和8.2倍；降低E-cadherin的表达；刺激合成FN。25和50 mmol/L的葡萄糖刺激HKC 12 h后，细胞培养上清液中TGF-β1浓度分别为(408.5±198.6)和(939.3±311.8) ng/L，呈剂量依赖性。抗TGF-β1抗体能够显著抑制高糖导致的HKC高表达α-SMA蛋白和FN及降低E-cadherin表达的作用。高表达Smad7蛋白的HKC转染细胞株在高糖的持续作用下，不能表达α-SMA和FN蛋白，E-cadherin也未见降低。细胞迁移实验表明，25和50 mmol/L高糖能够增加HKC迁移至Boyden小室膜下侧面的细胞数[(12.4±3.7)和（18.6±4.4)细胞/HP）]，与正常对照组[(3.0±0.8)细胞/HP]差异有统计学意义(P < 0.01)。抗TGF-β1多克隆抗体能够部分抑制高糖(50 mmol/L)造成的HKC细胞向Boyden小室膜下侧面的迁移[(11.9±5.2)细胞/HP]。高表达Smad7蛋白的HKC转染细胞株在高糖培养条件下迁移至Boyden小室膜下侧面的细胞数[（4.3±1.2）细胞/HP]与正常对照组差异无统计学意义。 结论 高糖能够诱导肾小管EMT，此作用与高糖刺激该细胞合成TGF-β1有关，阻止Smad信号途径能够拮抗TGF-β1介导的肾小管EMT的作用。     

Glutamatergic signaling maintains the epithelial phenotype of proximal tubular cells

Epithelial-mesenchymal transition (EMT) contributes to the progression of renal tubulointerstitial fibrosis. The N-methyl-d-aspartate receptor (NMDAR), which is present in proximal tubular epithelium, is a glutamate receptor that acts as a calcium channel. Activation of NMDAR induces actin rearrangement in cells of the central nervous system, but whether it helps maintain the epithelial phenotype of the proximal tubule is unknown. Here, knockdown of NMDAR1 in a proximal tubule cell line (HK-2) induced changes in cell morphology, reduced E-cadherin expression, and increased α-SMA expression. Induction of EMT with TGF-β1 led to downregulation of both E-cadherin and membrane-associated β-catenin, reorganization of F-actin, expression of mesenchymal markers de novo, upregulation of Snail1, and increased cell migration; co-treatment with NMDA attenuated all of these changes. Furthermore, NMDA reduced TGF-β1-induced phosphorylation of Erk1/2 and Akt and the activation of Ras, suggesting that NMDA antagonizes TGF-β1-induced EMT by inhibiting the Ras-MEK pathway. In the unilateral ureteral obstruction model, treatment with NMDA blunted obstruction-induced upregulation of α-SMA, FSP1, and collagen I and downregulation of E-cadherin. Taken together, these results suggest that NMDAR plays a critical role in preserving the normal epithelial phenotype and modulating tubular EMT.     

LeftyA真核表达载体的构建及其对转化生长因子-β1诱导人肾小管上皮细胞转分化的影响

目的 构建pcDNA3.1-LeftyA真核表达载体,观察其对转化生长因子-β1(TGF-β1)诱导人肾小管上皮细胞(HK-2)转分化(EMT)的影响.方法 基因克隆技术构建pcDNA3.1-LeftyA真核表达载体,将其瞬时转染HK-2细胞,TGF-β1(10μg/L)刺激后,观察细胞形态变化,检测E-钙黏蛋白(E-cadherin)、α-平滑肌肌动蛋白(α-SMA)基因及蛋白的表达.结果 TGF-β1刺激后HK-2细胞内E-cadherin mRNA和蛋白时间依赖性表达下调,α-SMA mRNA和蛋白时间依赖性表达上调,同时E-cadherin表达变化早于α-SMA;LeftyA蛋白可以显著抑制E-cadherin蛋白的下调表达(P＜0.05),其表达比同时间点单纯刺激组高17.6%;同时可逆转α-SMA蛋白的上调表达(P＜0.05),其蛋白表达比单纯刺激组低14.0%.结论 LeftyA蛋白可以抑制TGF-β1所致的EMT.

Abstract：

Objective To construct the eukaryotic expression vector for LeftyA and study the effects of LeftyA on epithelial to mesenchymal transition of human proximal tubular epithelial cells induced by transforming growth factor-β1 ( TGF-β1 ). Methods The pcDNA3. 1-LeftyA was constructed by recombinant DNA technique. After transfection with pcDNA3. 1-LeftyA HK-2 cells were stimulated by TGF-β1( 10 μg/L). The morphological changes, and the expression of E-cadherin, α-SMA and LeftyA mRNA and protein were observed and detected, respectively. Results TGF-β1 could markedly decrease the expression of E-cadherin mRNA and protein in HK-2 cells induced, and dramatically increase the expression of α-SMA mRNA and protein in a time-dependent manner. Forced expression of exogenous LeftyA led to a blockage of TGF-β1 -induced E-cadherin ( 17.6% ) suppression and α-SMA induction ( 14. 0% ). Conclusion Disruption of cell adherence is the beginning stage of EMT, and overexpression of LeftyA can suppress EMT induced by TGF-β1, which suggests a alprostadil role for LeftyA in TGF-β1-induced tubular EMT and renal fibrosis.     

间隙连接蛋白43表达改变对肾小管上皮细胞转分化的影响

目的 研究肾小管上皮细胞-肌成纤维细胞转分化（TEMT）过程中间隙连接蛋白43（connexin 43）表达和细胞间通讯功能的变化,以及上调connexin 43水平对TEMT的影响。方法 用转化生长因子（TGF）β1刺激人肾小管上皮细胞系（HKC）,检测connexin 43、上皮细胞标志物E-钙黏蛋白（E-cadherin）和肌成纤维细胞标志物α-SMA、vimentin的表达。用激光共聚焦显微镜荧光漂白恢复（FRAP）技术检测HKC细胞间通讯功能。通过pLNCX2- connexin 43病毒质粒转染HKC上调connexin 43的表达,检测以上各指标的变化,观察对TEMT的影响。结果 HKC经TGF-β1刺激后．其α-SMA和vimentin mRNA和蛋白质表达增强,而E-cadherin和connexin 43表达下降（P＜0．05）,细胞间通讯功能降低（P＜0．05）。connexin 43高表达后,TEMT程度明显减轻。结论 上调肾小管上皮细胞间通讯功能可部分减轻TEMT程度。     

Role of JLP on the epithelial to mesenchymal transition in renal tubular epithelial cells

Objective To observe the effect of JLP on transdifferentiation of human renal proximal tubular epithelial cells (HK-2), and to investigate the role of p38 MAPK signaling pathway in this process. Methods The knock-down plasmids of JLP were constructed. HK-2 cells were randomly divided into four groups: negative control cells (Ctrl-shRNA group), knock-down jlp cells (jlp-shRNA group), negative control cells with FGF-2 treatment (FGF-2 group) and knock-down jlp cells with FGF-2 treatment(jlp-shRNA+FGF-2 group). The expressions of JLP, E-cadherin, TGF-β1, α-SMA, p-p38 MAPK protein were detected by Western blotting．After the induction of FGF-2 for 24 hours, the expressions of α-SMA, COL-I, FN were detected by immunocytochemistry. Results Compared with Ctrl-shRNA group, the expression of JLP protein was significantly down-regulated in FGF-2 group. Compared with FGF-2 group, the expressions of TGF-β1, α-SMA, p-p38 MAPK protein were significantly up-regulated, while E-cadherin protein was significantly down-regulated (P＜0.05). Compared with FGF-2 group, the expressions of α-SMA, COL-I, FN immunostaining increased markedly in jlp-shRNA+FGF-2 group. Conclusion Scaffolding protein JLP is critical in preventing EMT in the course of fibrosis through the inhibition of p-p38 activation in HK-2 cells.     

法舒地尔对糖尿病大鼠肾小管上皮细胞转分化的影响

目的 观察法舒地尔对糖尿病大鼠肾小管上皮细胞转分化的影响并探讨其机制。 方法 将实验性Wistar大鼠随机分为正常对照组、糖尿病组、法舒地尔治疗组。3个月后处死动物,PAS染色法观察肾小球病理变化,Masson染色法观察肾间质病理变化;免疫组化观察肾脏皮质ROCKⅠ、α平滑肌肌动蛋白（α-SMA）、E钙黏蛋白（E-cadherin）的变化和β连环蛋白（β-catenin)的细胞定位改变;Western印迹法观察肾脏皮质p-MYPT1、α-SMA、E-cadherin、胞膜β-catenin蛋白的变化;实时定量PCR法观察ROCKⅠ、E-cadherin和总β-catenin的mRNA变化。 结果 法舒地尔治疗可改善肾间质纤维化状况。与正常对照组相比,糖尿病组大鼠肾皮质内p-MYPT1、α-SMA蛋白表达增强（均P < 0.01）;E-cadherin、胞膜β-catenin的蛋白表达减弱（均P < 0.01）;ROCK1、总β-catenin mRNA表达增强（均P < 0.01）;E-cadherin mRNA表达减弱（P < 0.01）。与糖尿病组相比,治疗组p-MYPT1、α-SMA蛋白表达减弱 （均P < 0.01）;E-cadherin、胞膜β-catenin的蛋白表达增强（均P < 0.05）;ROCK1、β-catenin mRNA表达减弱（均P < 0.01）;E-cadherin mRNA表达增强（P < 0.01）。 结论 法舒地尔可能通过抑制Rho激酶活性减轻糖尿病大鼠肾小管上皮细胞转分化和肾间质纤维化,该作用可能与法舒地尔恢复肾小管上皮细胞的黏附特性与紧密连接复合体有关。     

瘦素对人肾小管上皮细胞表型转化及纤维连接蛋白表达的影响

目的:通过观察瘦素(leptin)刺激对人肾小管上皮细胞(HK-2)表型转化和纤维连接蛋白(FN)表达的影响,探讨瘦素对HK-2细胞转分化的作用。方法:将体外培养的HK-2细胞分为对照组和不同浓度瘦素作用组。倒置显微镜下观察HK-2细胞形态学变化;实时荧光定量RT-PCR法检测HK-2细胞α-平滑肌肌动蛋白(α-smooth muscle actin,α-SMA)、E-钙黏蛋白(E-cadherin)和FN mRNA的表达水平;免疫细胞化学法检测HK-2细胞表达α-SMA的阳性细胞百分数;酶联免疫吸附法(ELISA)检测HK-2细胞培养液上清中FN的表达。结果:分别用50、100、200 ng/ml瘦素作用HK-2细胞48 h后,(1)HK-2细胞逐渐由椭圆形变成长梭形,类似肌成纤维细胞的形态;(2)RT-PCR结果表明,瘦素作用可以下调E-cadherin mRNA的表达,同时上调α-SMA、FN mRNA的表达。(3)免疫细胞化学结果表明,对照组HK-2细胞几乎不表达α-SMA,随着瘦素作用浓度的增加,α-SMA阳性的HK-2细胞百分数逐渐增多;(4)ELISA结果表明,对照组HK-2细胞有基础水平的FN分泌,各瘦素作用组上清液中FN的表达水平较对照组显著增加,且呈一定的剂量依赖关系。结论:瘦素可诱导肾小管上皮细胞转分化为肌成纤维细胞,分泌细胞外基质,从而可能参与肾间质纤维化的发生发展。     

CIP4对转化生长因子β1诱导的人肾小管上皮细胞-间充质转分化的影响

目的 观察骨架调节蛋白CIP4（Cdc42 interacting protein 4）对转化生长因子β1（TGF-β1）诱导的人肾小管上皮细胞-间充质转分化（EMT）的影响,并探讨其产生的机制。 方法 10 ?滋g/L TGF-β1刺激72 h诱导人近端肾小管上皮细胞（HK-2细胞）向间充质转分化。Western印迹法检测各组细胞内E-cadherin和α-SMA蛋白的表达。倒置显微镜观察细胞形态的变化。根据GenBank人CIP4的完全cDNA序列,设计1条特异性干扰CIP4表达的RNA片段（CIP4-siRNA）和含野生型CIP4的重组真核表达质粒（pcDNA3.1-hCIP4）,利用lipofactamine 2000将其转染HK-2细胞。Western 印迹法检测对照组、TGF-β1刺激组、CIP4-siRNA转染组、pcDNA3.1-CIP4转染组细胞内CIP4、E-cadherin和α-SMA蛋白的表达,共聚焦显微镜观察 E-cadherin和α-SMA蛋白的分布改变;用PI3K-Akt特异性抑制剂渥曼青霉素（wortmannin） 1 μmol/L干预TGF-β1刺激的HK-2细胞48 h,Western 印迹法检测对照组和干预组CIP4表达的变化。 结果 TGF-β1干预后HK-2细胞E-cadherin蛋白表达显著减少（P ＜ 0.05）,α-SMA蛋白表达显著增多（P ＜ 0.05）,细胞形态由典型的上皮细胞向肌成纤维细胞转变,表明TGF-β1诱导肾小管上皮细胞EMT模型成功。CIP4-siRNA抑制TGF-β1诱导的HK-2细胞表达CIP4后,E-cadherin蛋白表达显著增多（P ＜ 0.05）,α-SMA蛋白表达显著减少（P ＜ 0.05）,部分逆转了上述TGF-β1诱导的肾小管上皮细胞EMT。pcDNA3.1-hCIP4转染使CIP4高表达后,HK-2细胞E-cadherin蛋白表达显著减少（P ＜ 0.05）,α-SMA蛋白表达显著增多（P ＜ 0.05）,诱导了肾小管上皮细胞EMT。用渥曼青霉素干预TGF-β1刺激的HK-2细胞48 h,CIP4可能蛋白表达显著减少（P ＜ 0.05）。 结论 TGF-β1通过PI3K-Akt途径上调CIP4表达,CIP4可能进一步参与TGF-β1诱导的肾小管上皮细胞EMT过程。     

Role of β-catenin signaling pathway in the epithelial to mesenchymal transition induced by parathyroid hormone in renal tubular epithelial cells

Objective To investigate the effect of parathyroid hormone (PTH) on the epithelial to mesenchymal transition (EMT) in human renal proximal tubular epithelial cells (HK-2 cells), and determine the role of β-catenin signaling pathway. Method The expression of α-smooth muscle actin (α-SMA), E-cadherin and β-catenin in HK-2 cells was measured by real-time PCR, Western blotting and immunofluorescence technique. The signaling pathway by which PTH activated EMT in HK-2 cells was identified by using synthetic β-catenin siRNA. Results Parathyroid hormone (10-10 mol/L) increased α-SMA expression and decreased E-cadherin expression in HK-2 cells (P＜0.01, respectively). Untreated cells showed the expression of E-cadherin, whereas α-SMA staining was noticeably increased in cells treated with PTH. β-catenin activity was significantly increased after exposed to PTH. Theα-SMA expression was decreased strongly and E-cadherin expression was increased after β-catenin siRNA transfection (all P＜0.05). Conclusion PTH significantly induces epithelial to mesenchymal transition in HK-2 cells throughβ-catenin signaling pathway.     

NADPH氧化酶在转化生长因子β1诱导大鼠肾小管上皮细胞转分化中的作用

目的探讨NADPH氧化酶在转化生长因子β1（TGF-β1）诱导大鼠肾小管上皮细胞（NRK-52E）转分化中的作用。方法用TGF-β1（10μg/L）刺激NRK-52E细胞不同时间,观察α-平滑肌肌动蛋白（α-SMA）、E-钙黏蛋白（E-cadherin）、纤溶酶原激活物抑制剂1（PAI- 1）及Ⅰ型胶原（Col-Ⅰ）的表达。部分实验中细胞在TGF-β1刺激前用NADPH氧化酶抑制剂DPI预处理1 h。用激光共聚焦显微镜观察细胞内活性氧（ROS）的产生。用RT-PCR方法检测NADPH氧化酶p22phox、gp91phox、p47phox和p67phox亚单位mRNA的表达。α-SMA、E-cadherin、PAI-1及Col-ⅠmRNA及蛋白的表达分别采用RT-PCR、Western印迹和细胞免疫化学检测。结果TGF-β1可显著上调NADPH氧化酶p67phox亚单位mRNA的表达,8 h及24 h时分别为对照组的2.43倍及3.59倍（P〈0.01）。TGF-β1可显著促进细胞ROS的产生,5 min时已是对照组的2.5倍（P〈0.05）。DPI预处理同时可显著逆转TGF-β1诱导NRK-52E细胞ROS的产生（P〈0.05）、α-SMA的表达上调、E-cadherin的表达下调以及PAI-1和Col-Ⅰ的表达上调。结论TGF-β1可促进NRK-52E细胞增加ROS的产生。ROS介导了TGF-β1诱导NRK-52E细胞的转分化,促进肾脏纤维化。     

低密度脂蛋白和氧化低密度脂蛋白诱导人肾小管上皮细胞转分化的通路研究

目的探讨低密度脂蛋白（LDL）和氧化（OX）LDL是否可诱导人肾小管上皮细胞转分化及其可能机制。方法体外培养的第2代肾小管上皮细胞随机分为（1）阴性对照组；（2）LDL（50mg／ml）组；（3）oxLDL（50mg／ml）组；（4）LDL（50mg／m1）＋PD98059（5μmol／L）组；（5）oxLDL（50mg／ml）＋PD98059（5μmol／L）组。应用形态学、免疫荧光、Western印迹观察LDL和oxLDL刺激小管细胞角蛋白（cytokerafin）、E-钙粘糖蛋白（cadhefin）、α-SMA和波形蛋白（vimenfin）表达的改变、Ⅰ型胶原产生的改变，及其与ERK1／2MAPK通路活化的关系。结果OXLDL较LDL有更强的致小管上皮细胞转分化的作用，与对照组相比。细胞中上皮细胞标记cytokeratin和E-cadherin表达减少，间充质细胞标记α-SMA和vimentin明显增加，Ⅰ型胶原产生增多（P〈0．05）。LDL和oxLDL刺激组细胞中ERK1／2MAPK和GSK-3β磷酸化活化较对照组明显增强（P〈0．05）；β-catenin发生细胞核内转移。MAPK抑制剂PD98059可抑制GSK-3β的磷酸活化，并几乎完全阻断oxLDL诱导的肾小管上皮细胞转分化，但对LDL诱导的小管上皮细胞转分化只有部分阻断作用。结论本研究首次在体外观察到（1）oxLDL可诱导肾小管细胞上皮细胞转分化和Ⅰ型胶原的产生，作用明显强于LDL；（2）ERK1／2MAPK、GSK-3β和β-catenin组成一条信号通路调节LDL和oxLDL诱导的小管上皮细胞转分化。     

Expression of β-catenin in regenerating renal tubules of cisplatin-induced kidney failure in rats

Background

β-Catenin is a multi-functional protein involved in nephrogenesis and also plays important roles in renal injury. Here, the expression of β-catenin was investigated in the proximal renal tubular epithelial cells in cisplatin (CDDP)-induced acute kidney injury (AKI) and chronic kidney injury (CKI), because CDDP-induced renal lesions were characterized by proximal renal tubular epithelial degeneration/regeneration and subsequent interstitial fibrosis.

Methods

F344 rats were treated with CDDP. The expression of β-catenin and proliferative (Ki67) or fibrogenic [vimentin, α-smooth action (α-SMA)] markers was analyzed by immunolabeling.

Results

β-Catenin, vimentin and Ki67 were not seen in the proximal renal tubules of control rats. Interestingly, in CDDP-induced AKI, the regenerating proximal renal tubular epithelial cells reacting strongly with Ki67 expressed membranous or cytoplasmic β-catenin and also showed a positive reaction to vimentin but not to α-SMA. In CDDP-induced CKI, the epithelial cells of abnormally dilated or atrophied renal tubules did not react to β-catenin or Ki67, but showed positive reactions to vimentin and α-SMA. β-Catenin mRNAs were significantly increased in AKI and significantly decreased in CKI.

Conclusion

Newly expressed β-catenin in the proximal renal tubules after AKI may participate in functional regeneration. In CKI, epithelial cells of abnormal renal tubules did not express β-catenin but reacted to vimentin, and α-SMA might indicate the epithelial–mesenchymal transition (EMT) formation, because α-SMA is usually expressed in myofibroblasts forming via EMT. The presence or absence of β-catenin expression would become a marker for the EMT phenomenon in progressive renal fibrosis.

     

高糖通过血清和糖皮质激素诱导的蛋白激酶1通路促进人近端肾小管上皮细胞合成纤连蛋白

目的 研究血清和糖皮质激素诱导的蛋白激酶1(SGK1)在高糖诱导人近端肾小 管上皮细胞(HKC)产生纤连蛋白(FN)中的作用,探讨SGK1在糖尿病肾病(DN)肾小管间质纤 维化中的作用机制。方法 将带有SGK1显性激活型突变体质粒(pIRES2-EGFP-S422DSGK1 mutant, SD)和带有SGK1显性失活型突变体质粒(pIRES2-EGFP-K127NSNSGK1 mutant,KN)分别瞬时转染 HKC;同时,设空质粒(pIRES2-EGFP,FP)转染组和未转染组(NT)为对照。分别用正常糖(NG, 5.5 mnlol／L D-葡萄糖)和高糖(HG,25 mmol/L D-葡萄糖)刺激8 h后,采用RT-PCR和Western 印迹来观察SGK1和FN的mRNA及蛋白的表达。结果 正常葡萄糖环境下转染SD和KN后, HKC合成的FN mRNA和蛋白的表达没有显著性改变。高糖环境下,转染SD的HKC与其它组 比较,其SGK1mRNA表达显著性增高(P<0.01),SGK1蛋白过度活化(P<0.01),其FN mRNA和 蛋白的表达显著增加(P<0.01)。转染KN的HKC与其它高糖组HKC比较,其活化的SGK1蛋 白显著减少(P<0.01),其合成FN mRNA和蛋白亦显著减少(P<0.01)。结论 高糖诱导HKC 的FN mRNA和蛋白的表达增加是依赖于SCK1的表达与活化,提示在DN中,高糖能通过SGK1 介导的信号通路来诱导人近端肾小管上皮细胞过度合成FN,促进肾小管间质纤维化。     

Hepatocyte growth factor modulates matrix metalloproteinases and plasminogen activator/plasmin proteolytic pathways in progressive renal interstitial fibrosis

Evidence suggests that hepatocyte growth factor (HGF) ameliorates renal fibrosis in animal models of chronic renal disease by promoting extracellular matrix catabolism. This study examined the molecular mechanisms of HGF-induced alterations in matrix degradation both in vitro and in vivo. In vitro, HGF increased the collagen catabolizing activity of human proximal tubular epithelial cells (HKC) that were treated with TGF-beta1. Increased collagen catabolism was associated with enhanced activity of both matrix metalloproteinases (MMP) and plasminogen activators (PA)/plasmin proteolytic pathways. HGF abrogated TGF-beta1-induced production of the profibrotic tissue inhibitor of metalloproteinase-2 (TIMP-2) and plasminogen activator inhibitor-1 (PAI-1). In addition, HGF induced the production of MMP-9. In vivo, continuous infusion of HGF in the rat remnant kidney model ameliorated renal fibrosis and tubulointerstitial collagen deposition. This was associated with increased tubular expression of MMP-9, enhanced in situ gelatinolytic activity, partially restored plasmin activity and decreased expression of TIMP-2 and PAI-1 in tubular cells, and upregulation of renal TIMP-3 expression. Conversely, blocking of endogenous HGF by an anti-HGF neutralizing antibody increased renal fibrosis and interstitial collagen. This was accompanied by decreased tubular expression of MMP-9, less in situ proteolytic activity, and elevated expression of TIMP-2 and PAI-1 in tubular cells. Collectively, these findings demonstrate that HGF ameliorates renal fibrosis by enhancing extracellular matrix catabolism via both MMP and the PA/plasmin proteolytic pathways.     

DJ-1癌基因在肾间质纤维化中表达的实验研究

目的 观察DJ-1癌基因在肾纤维化过程中表达水平、细胞内定位及高表达 DJ-1基因对人肾小管上皮细胞E钙黏蛋白（E-cadherin）、波形蛋白（vimentin）蛋白表达和β连环素（β-catenin）酪氨酸磷酸化水平的影响。 方法 体外实验以人肾小管上皮细胞为研究对象,10 μg/L TGF-β1刺激72 h诱导人肾小管上皮细胞转分化;Western印迹法检测正常组和TGF-β1干预组细胞内E-cadherin、vimentin和DJ-1蛋白表达;RT-PCR法检测两组细胞内DJ-1 mRNA表达水平;应用激光共聚焦显微镜观察DJ-1在细胞内的定位。体内实验以SD大鼠为研究对象,5/6肾切除法制作慢性肾纤维化模型;常规检测BUN和Scr水平;Masson染色检测肾组织纤维化水平;免疫组化法检测肾组织内DJ-1蛋白的表达和分布。脂质体法介导含野生型DJ-1基因的重组真核表达质粒pEGFP-N1-DJ-1或空载体转染人肾小管上皮细胞,倒置荧光显微镜和Western 印迹法鉴定转染效率后,Western 印迹法检测正常组、pEGFP-N1-DJ-1转染组和空载体转染组细胞内E-cadherin、vimentin蛋白的表达及各组β-catenin酪氨酸磷酸化水平。 结果 正常组细胞表达E-cadherin和DJ-1,几乎不表达vimentin;TGF-β1干预组细胞表达vimentin,表达较少E-cadherin,DJ-1 mRNA和蛋白表达均较正常组细胞显著增多（P < 0.05）。DJ-1在正常细胞内大多分布在细胞质,部分分布在细胞核;在转分化细胞内胞质和胞核内表达均有增加,且胞核内增加更显著。假手术组大鼠肾功能正常,肾组织内未见纤维组织,DJ-1主要表达于肾小管,肾小球内几乎没有表达。模型组大鼠肾功能不全,肾组织内可见明显纤维化结构,肾小管内DJ-1表达明显增加。pEGFP-N1-DJ-1转染组较正常组和空载体转染组细胞内DJ-1和vimentin蛋白表达明显增加且β-catenin酪氨酸磷酸化水平升高, 而 E-cadherin蛋白表达减少。 结论 DJ-1基因高表达可能促进了肾间质纤维化。     

青藤碱对白介素1β诱导的肾小管上皮细胞骨架变化和明胶酶活性的影响

目的 探讨青藤碱干预炎症介质诱导的肾小管上皮细胞表型转化的作用。 方法 用IL-1β(10 ng/ml)刺激小鼠肾小管上皮细胞株(MCT)和原代小鼠肾小管上皮细胞，并用青藤碱(10、100、500 μmol/L)进行干预。应用四唑盐(MTT)法测定青藤碱的细胞毒性。用免疫细胞化学法、Western印迹和RT-PCR分别测定细胞α-平滑肌肌动蛋白(α-SMA)、波形蛋白(Vim)蛋白和基因表达；明胶酶谱法测定明胶酶——基质金属蛋白酶类活性。 结果 IL-1β能够使肾小管上皮细胞α-SMA、Vim蛋白质合成和基因表达显著上调，明胶酶活性亦同时增强；各个浓度的青藤碱均可显著降低α-SMA、Vim蛋白质和基因的表达以及明胶酶活性。结论 青藤碱可抑制免疫炎症因子诱导的肾小管上皮细胞发生表型转化和降低明胶酶活性，可在一定程度上阻止肾小管上皮细胞迁移，防止肾小管萎缩，从而在防治肾小管间质纤维化中发挥其作用。     

血管内皮生长因子C参与肾间质纤维化的进程

目的探讨血管内皮生长因子C（VEGF-C）在大鼠。肾小管上皮细胞向间充质细胞转化（EMT）过程中的变化及其作用通路,并利用动物模型研究血管紧张素Ⅱ受体拮抗剂替米沙坦对VEGF-C的影响,从而探讨VEGF-C在肾间质纤维化中的作用。方法体外培养大鼠肾小管上皮细胞（NRK52E）,用转化生长因子B1（TGF-β1）孵育不同时间,观察其对VEGF-C、上皮型钙黏蛋白（E-cadherin）、波形蛋白（vimentin）、磷酸化AKT（P-AKT）等表达的影响,并在TGF-131作用同时加入PBK抑制剂Wortmannin,观察上述指标的变化;用单侧输尿管结扎术（UUO）制作SD大鼠肾间质纤维化模型,将21只大鼠随机分为假手术组、模型组和替米沙坦治疗组,每组7只。2周后,用免疫组织化学法检测α平滑肌肌动蛋白（mSMA）及VEGF-C在肾组织的分布,用RT-PCR和Westernblot—ring法检测其mRNA和蛋白表达。结果TGF-β1促进EMT的同时促进VEGF-C的表达增加。加入Wortmannin后EMT被抑制,同时VEGF-C的表达减低。动物模型组α-SMA和VEGF-C表达较假手术组高,替米沙坦治疗组α-SMA和VEGF-C表达较模型组低。结论TGF-β1可通过P13K—AKT通路促进VEGF-C的表达,VEGF-C与α-SMA的变化有同步性,提示VEGF-C可能参与肾间质纤维化的进程。     

High uric acid induces phenotypic transition of renal tubular cells via PI3K/Akt signaling pathway

Objective To investigate the effect and the mechanism of epithelial-mesenchymal transition (EMT) in renal tubular cells induced by uric acid. Methods Normal rat kidney tubular cell line (NRK-52E) were exposed to different concentrations of uric acid (100, 200, 400, 600, 800 μmol/L UA) for 48 hours to induce EMT. Morphological changes of the NRK-52E cells were examined under an inverted phase contrast microscope. The protein expression of E-cadherin, α-SMA, p-Akt and Akt were detected by Western blotting. The distribution of E-cadherin and α-SMA were detected by immunofluorescence. NRK-52E cells were pretreated by different concentrations of LY294002(0, 2.5, 5, 10, 15 μmol/L), the inhibitor of PI3K/p-Akt signaling pathway, and then processed by uric acid (400 μmol/L) for 48 hours. Western blotting was used to detect the protein expression of p-Akt and Akt. NRK-52E cells were then divided into four groups: normal group (N), uric acid group (UA), LY294002 group (LY), uric acid with LY294002 group (UA+LY). The protein expression of E-cadherin and α-SMA were detected by Western blotting, the distribution of E-cadherin, α-SMA and p-Akt were detected by immunofluorescence. Results There was abundant cellular expression of E-cadherin in unstimulated renal tubular cells whereas its expression was significantly decreased in uric acid-stimulated cells (P＜0.05). In addition, uric acid induced de novo expression of α-SMA in contrast to almost negative staining in untreated cells (P＜0.05). p-Akt were obviously increased in high uric acid group (P＜0.05) and Akt changed not significantly (P＞0.05). NRK-52E cells transformed into elongated fibroblast-like cells from cuboidal clustered epithelial cells. These indicated that uric acid has induced EMT and activated PI3K/p-Akt signaling pathway in NRK-52E cells. However, the above effects of uric acid were abolished when p-Akt was blocked by the PI3K inhibitor (10, 15 μmol/L LY294002), indicated that LY294002 has reversed the trend of EMT. Conclusions High uric acid induces phenotypic transition of renal tubular cells probably via activating PI3K/Akt signaling pathway.