p44/42和p38 MAPKs在骨髓间充质干细胞向成骨细胞分化中发挥不同的功能

目的 观察p44／42MAPK、p38MAPK通路在维生素C(Vit C)、β-磷酸甘油(β-GP)诱导骨髓间充质干细胞(BMSCs)向成骨细胞分化过程中的作用。方法 用[^3H]-甲基胸腺嘧啶掺入率法反映细胞增殖情况；洲定碱性磷酸酶活性与钙沉积积反映细胞向成骨细胞分化状态；有Western-blotting法反映MAPK的表达情况。结果 与溶剂对照组相比．在促成骨细胞分化剂Vit C，β-GP作用下，骨髓间充质干细胞(BMSCs)p44／42MAPK、p38MAPK通路均提前5d激活。p44／42MAPK通路阻断剂(PID8059)明显减少[^3H]-甲基胸腺嘧啶掺入率，抑制BMSCs的增殖；而p38MAPK通路的阻断剂(SB203580)则显著降低ALP活性及钙沉积量．抑制BMSCs向成骨细胞的分化。结论 p44／42MAPK通路在BMSCs的增殖过程中起苇要作用，而p38MAPK通路可能与BMSCs向成骨细胞分化调节有关。     

MAPK信号通路在淫羊藿甙促进成骨细胞Cbfa1蛋白表达中的作用

目的 观察淫羊藿甙对体外培养大鼠成骨细胞丝裂原活化蛋白激酶(mitogen-activated protein kinase,MAPK)信号通路的影响以及MAPK信号通路在淫羊藿甙促成骨细胞核心结合因子α1(core binding factor-1,Cbfa1)蛋白表达中的作用,以探讨淫羊藿甙对成骨细胞作用的信号传导机制.方法 用酶消化法分离24 h内新生SD大鼠颅盖骨成骨细胞,进行原代培养.在培养液中加入淫羊藿甙(10 ng/mL),作用于成骨细胞5 min、10 min、30 min、60 min,抽提总蛋白,用Western blot法检测细胞中ERK、p-ERK、P38和p-P38蛋白的表达.用雌二醇(10-8 mol/L)作用于成骨细胞5 min、10 min、30 min,同上法检测细胞中ERK、p-ERK、P38和p-P38蛋白的表达.用淫羊藿甙(10 ng/mL)、雌二醇(10-8 mol/L)和u0126或SB203580单独或共同干预成骨细胞24 h,抽提核蛋白,用Western blot法检测Cbfa1蛋白的表达.结果 ①淫羊藿甙作用于成骨细胞,30 min时可促进ERK蛋白的磷酸化,并可持续至60 min,和空白组比较,差异有显著性(P<0.05);淫羊藿甙作用于成骨细胞,5 min时即可促进P38蛋白的磷酸化,在30 min时达高峰,并可持续至60 min,和空白组比较,差异有显著性(P<0.05).②雌二醇作用于成骨细胞,在30 min时可促进ERK蛋白的磷酸化,和空白组比较,差异有显著性(P<0.05);雌二醇作用于成骨细胞,在10 min时可促进P38蛋白的磷酸化,并可持续至30 min,和空白组比较,差异有显著性(P<0.05).③淫羊藿甙和雌二醇均能促进成骨细胞中Cbfa1蛋白的表达,和空白组相比,差异有显著性(P<0.05).u0126和SB203580可以抑制淫羊藿甙和雌二醇促进Cbfa1蛋白表达的作用.结论 ①淫羊藿甙和雌二醇均可以激活成骨细胞中ERK/MAPK和P38/MAPK信号通路;②淫羊藿甙和雌二醇均能促进成骨细胞中核转录因子Cbfa1的表达,并且ERK/MAPK和P38/MAPK信号通路参与了此过程.     

两种不同病理类型肾病患者尿蛋白诱导肾小管上皮细胞上调表达趋化因子及其分子信号机制研究

目的 观察不同病理类型肾病患者尿蛋白对人近端肾小管上皮细胞（HK-2）分泌趋化因子的影响并探讨其分子信号机制。 方法 所有患者均经临床和肾穿刺活检确诊为原发性局灶节段性肾小球硬化（FSGS）或微小病变性肾病（MCD）。以超滤法浓缩提取患者尿中总蛋白，分别刺激体外培养的HK-2细胞。RT-PCR检测调节正常T细胞表达和分泌的细胞因子（RANTES）及巨噬细胞移动抑制因子（MIF）的mRNA水平。免疫荧光、ELISA及流式细胞仪检测蛋白水平的表达。Western 印迹法检测p38 MAPK和胞外信号调节激酶（ERK）水平。特异性抑制剂SB203580抑制p38磷酸化；PD98059则用于抑制ERK磷酸化。 结果 两种尿蛋白成分有差异，FSGS患者尿蛋白中含有更多的大分子量蛋白。两种尿蛋白均刺激HK-2细胞RANTES及MIF表达上调，而FSGS患者尿蛋白刺激作用更强。两种尿蛋白均显著激活HK-2细胞内ERK和p38 MAPK信号通路。特异性抑制剂分别抑制ERK或p38 MAPK的活化后，FSGS患者尿蛋白介导的RANTES和MIF的上调表达作用可被SB203580或PD98059抑制，而MCD患者尿蛋白的刺激作用却仅能被SB203580所阻断。 结论 FSGS肾病患者的尿蛋白比MCD患者的尿蛋白有更强的上调HK-2细胞RANTES及MIF表达的作用。两种尿蛋白介导趋化因子上调表达的分子信号机制存在差异。     

微RNA-23a通过缝隙连接蛋白43对颈椎后纵韧带细胞骨向分化的作用机制

目的 探讨微RNA（miR）-23a通过缝隙连接蛋白43（Cx43）对颈椎后纵韧带细胞骨向分化的作用及相关机制。方法 选取本院收治的50例间断型颈椎后纵韧带骨化症（OPLL）患者（OPLL组）、50例颈椎外伤非OPLL患者（对照A组）和50例颈椎病非OPLL患者（对照B组）颈椎后纵韧带组织，培养后纵韧带细胞，实时荧光定量聚合酶链反应（qRT-PCR）检测3组细胞miR-23a、Cx43 mRNA的表达，采用Western blotingt检测Cx43蛋白的表达。取OPLL组对数期后纵韧带细胞，分别转染miR-23a agomir质粒（miR-23a过表达组）、miR-23a antagomir质粒（miR-23a低表达组）、agomir NC质粒（转染对照组），未经处理的后纵韧带细胞为空白组。采用双荧光素酶实验验证miR-23a与Cx43的靶向关系；采用碱性磷酸酶（ALP）染色检测矿化情况；采用Western blotingt检测p38丝裂原活化蛋白激酶（p38 MAPK）、磷酸化p38 MAPK（p-p38 MAPK）、细胞外信号调节激酶（ERK1/2）、磷酸化ERK1/2（p-ERK1/2）的蛋白表达。结果 与对照A、B组比较，OPLL组miR-23a表达降低，Cx43 mRNA及蛋白表达升高，差异均有统计学意义（P < 0.05）。与空白组、转染对照组比较，miR-23a过表达组miR-23a表达量升高、Cx43 mRNA表达量降低，miR-23a低表达组miR-23a表达量降低、Cx43 mRNA表达量升高，差异均有统计学意义（P < 0.05）。双荧光素酶实验显示，miR-23a可有效抑制野生型质粒荧光素酶活性；与空白组、转染对照组比较，miR-23a过表达组矿化面积百分比、p-p38 MAPK/p38 MAPK蛋白表达、p-ERK1/2/ERK1/2蛋白表达降低，miR-23a低表达组矿化面积百分比、p-p38 MAPK/p38 MAPK蛋白表达、p-ERK1/2/ERK1/2蛋白表达升高，差异均有统计学意义（P < 0.05）。 结论OPLL病理条件下，颈椎后纵韧带细胞中miR-23a异常低表达，通过靶向上调Cx43激活MAPK信号通路，促进成骨分化。     

17 β雌二醇通过丝裂原活化蛋白激酶抑制前列腺癌细胞系PC3增殖

目的探讨丝裂原活化蛋白激酶在17β雌二醇(E2)抑制前列腺癌PC3细胞生长中的作用。方法检测不同浓度E2作用不同时间后PC3细胞生长抑制率。流式细胞仪分析细胞周期分布,TUNEL染色检测凋亡。Western blot检测ERK1/2,JNK和p38活性。RT-PCR法检测雌激素受体(ER)α、ERβ、P21WAF1和cyclinD1的表达。结果E2抑制PC3细胞增殖,并且可以激活ERK1/2、JNK和p38。处理因素作用48h后,对照组、E2、E2 PD98059、E2 SP600125、E2 SB203580组细胞的凋亡率分别为(0.9±0.1)%;(23.0±1.4)%;(30.0±1.2)%;(10.6±0.8)%和(14.6±0.7)%,(P<0.05)。E2使细胞阻滞在G1期,PD98059、SP600125、SB203580分别预处理1h后细胞分别进一步阻滞在G1期;轻度阻滞在G1期和进入S期。RT-PCR发现PC3细胞表达ERα和ERβ,E2、E2 PD98059、E2 SP600125、E2 SB203580组中cyclinD1、P21WAF1基因表达分别为对照组的(0.42±0.03)、(3.13±0.02)倍;(0.21±0.03)、(3.08±0.05)倍;(0.43±0.01)、(1.31±0.04)倍;(2.81±0.02)、(3.14±0.02)倍(P<0.05)。结论E2激活JNK增加P21WAF1基因表达,并激活p38抑制cyclinD1表达,使细胞阻滞在G1期,JNK和p38通路还介导E2引起PC3细胞凋亡。同时E2又可激活ERK1/2,轻度拮抗上述作用。     

MEK/ERK信号通路在吡咯喹啉醌促雪旺细胞增殖中的作用

目的 探讨MEK/ERK信号通路在吡咯喹啉醌促雪旺细胞增殖过程中的作用. 方法 体外培养雪旺细胞,S-100免疫荧光鉴定;Western blot检测MEK下游因子ERK1/2磷酸化激活形式(p-ERK1/2)的表达;MEK抑制剂(PD98059)阻断该通路后检测p-ERK1/2的表达;MTT法检测经PD98059阻断MEK通路后雪旺细胞的增殖情况. 结果 吡咯喹啉醌可激活雪旺细胞内MEK/ERK信号通路,在加入吡咯喹啉醌1 h后p-ERK1/2表达最高;吡咯喹啉醌在1～500 nmol/L范围内可使p-ERK1/2表达增加,1 000 nmol/L时与对照组比较差异无统计学意义,10 000 nmol/L时则表现为抑制作用(P＜0.05);经PD98059阻断MEK通路后p-ERK1/2的上调效应消失(P＜0.05).而且加入PD98059阻断MEK通路后吡咯喹啉醌对雪旺细胞的促增殖效果减弱. 结论 吡咯喹啉醌可激活雪旺细胞MEK/ERK信号通路,且该通路在吡咯喹啉醌促雪旺细胞增殖过程中发挥作用.     

通过p38MAPK信号通路探讨仙灵骨葆胶囊对MC3T3-E1成骨分化的影响

目的 探讨仙灵骨葆胶囊含药血清对小鼠胚胎成骨细胞前体细胞（MC3T3-E1）增殖分化的影响及与p38MAPK信号通路的关系。方法 用仙灵骨葆胶囊含药血清干预MC3T3-E1,CCK8法筛选最佳干预时间及浓度,试剂盒检测各组细胞ALP活性。将细胞分为A、B、C、D 4组,分别加入10%含药血清、10%空白血清、10%含药血清+SB203580、10%空白血清+SB203580,利用免疫印迹法（Western blot）检测p38丝裂原活化蛋白激酶（p38）、磷酸化p38（p-p38）、成骨相关转录因子2（Runx2）、骨形态发生蛋白2（BMP-2）的蛋白表达量,荧光定量PCR检测p38、Runx2和BMP-2 mRNA的表达水平。结果 与空白血清组相比,不同浓度的仙灵骨葆胶囊含药血清均能促进MC3T3-E1的增殖分化,提高ALP的活性,其中10%含药血清干预36 h的作用最为明显（P＜0.05）;与B组比较,A组p38、p-p38、Runx2、BMP-2蛋白及p38、Runx2、BMP-2 mRNA的表达明显增高（P＜0.05）;加入信号通路阻断剂SB203580后,C组与D组上述指标的表达明显降低（P＜0.05）;与C组相比,D组p38、p-p38、Runx2、BMP-2蛋白及p38、Runx2、BMP-2 mRNA表达更低（P＜0.05）。结论 仙灵骨葆胶囊含药血清能促进MC3T3-E1的分化生长,其作用机制可能与激活p38MAPK信号通路、上调成骨相关因子Runx2、BMP-2的表达有关。     

脂联素通过MAPK途径诱导人成骨细胞分化的研究

目的 本研究观察脂联素（adiponectin）对成骨细胞分化作用。方法分化指标碱性磷酸酶（alkaline phosphatase，AIJP）用酶联免疫吸附试验（ELISA）检测；并观测Adiponectin对矿化的影响。细胞丝裂原活化蛋白激酶（mitogen-activated proteinkinase，MAPK）信号转导阻断剂U0126。SB203580和SP600125干预，观察Adiponectin对成骨细胞分化作用的变化。p-JNK，JNK，p-p38，p38，p-ERKl／2，ERKl／2用WesternBlot检测。结果Adiponectin可提高ALP活性，并促进矿化结节形成。Adiponectin作用于成骨细胞诱导p38和JNK磷酸化，而p38抑制剂SB203580可减轻Adiponectin对成骨细胞ALP活性的影响。结论Adiponectin通过P38信号转导途径诱导人成骨细胞分化。     

转化生长因子β1对肾小管上皮细胞中结缔组织生长因子基因启动子活性的影响

目的探讨转化生长因子[β1（TCF-β1）对人近端肾小管上皮细胞系HK-2中结缔组织生长因子（CTGF）基因启动子活性的调控作用，以及丝裂原激活蛋白激酶（MAPK）途径对该生长因子作用的影响。方法构建含有人类CTGF基因启动子的报告基因pCTGF-luc，将其瞬时转染HK-2细胞。通过检测荧光素酶的活性观察TGF-β1和MAPK途径抑制剂对CTGF基因启动子活性的影响。结果TGF-β1以剂量和时间依赖方式上调HK-2中CTGF基因启动子的活性。最佳刺激浓度是5ng／ml，最佳刺激时间为12h，荧光素酶相对活性分别为对照组的1．82倍和2．10倍（P〈0．05）。应用PD98059、SB203580和SP600125分别特异性抑制MAPK途径的胞外信号调节蛋白激酶（ERK）、蛋白激酶p38（p38MAPK）和c-Jun-氨基末端激酶（JNK）通路，对TGF-β1上调CTGF启动子活性的作用有不同影响。PD98059显著增加HK-2中pCTGF-luc的基础活性．并在一定浓度范围内（0．5～10μmol／L）促进TGF-β1的上调作用。SB203580对pCTGF-luc基础活性无影响，但以剂量依赖方式显著抑制TGF-β1的激活效应。而SP600125对基础状态和TGF-β1刺激下CTGF基因启动子活性无影响。结论TGF-β1以剂量和时间依赖方式上调HK-2中CTGF基因启动子活性，在转录水平调节CTGF表达。MAPK途径的ERK和p38MAPK通路可影响TGF-β1的这一调控作用。     

丝裂原活化蛋白激酶对大鼠成骨细胞TRPV6表达的影响

目的探讨丝裂原活化蛋白激酶对大鼠成骨细胞瞬时性受体电位香草精受体6（transient receptor poten-tial vanilloid receptor 6,TRPV6）表达的影响。方法采用Wistar大鼠乳鼠,连续酶消化法提取成骨细胞并培养。根据组织形态学、改良Kaplow氏成骨细胞碱性磷酸酶染色、矿化结节茜素红染等方法进行鉴定。实验分组：a）正常对照组;b）PD组（PD98059 5μmol/L;PD98059 10μmol/L;PD98059 20μmol/L）;c）SB组（SB203580 5μmol/L;SB20358010μmol/L;SB203580 20μmol/L）;d）PD＋SB组（PD98059 5μmol/L＋SB203580 5μmol/L;PD98059 10μmol/L＋SB203580 10μmol/L;PD98059 20μmol/L＋SB203580 20μmol/L）。细胞计数法、MTT法检测细胞活性,RT-PCR检测成骨细胞TRPV6 mRNA。所得数据用x-±s表示,采用t检验进行统计学分析。结果随着PD98059和/或SB203580浓度的增加,细胞增殖活性有下降的趋势,二者联合作用时细胞活性低于二者单独作用。细胞计数法检测显示,PD98059与SB203580联合作用时,三种组合中细胞数均显著低于空白对照组,P〈0.01;同时也明显低于二者单独作用组细胞数量。碱性磷酸酶染色显示,联合用药组较单独用药细胞数明显减少,细胞体积变小,突起狭长,ALP染色阳性颗粒减少,随药物作用浓度增加上述变化更加显著。茜素红染色显示,钙结节与对照组比较数量少、体积小;10、20μmol/L联合作用组,细胞数减少更加明显,无钙结节形成。SB203580与PD98059二者联合应用显著抑制TR-PV6 mRNA的表达,5 mmol/L联合作用组即可明显抑制,随着作用浓度增加TRPV6 mRNA的表达量逐渐减少。结论 p44/42途径阻断剂PD98059能抑制成骨细胞增殖,明显降低成骨细胞TRPV6 mRNA表达,减少钙结节形成。p38途径阻断剂SB203580能抑制成骨细胞增殖,明显降低成骨细胞TRPV6 mRNA表达,减少钙结节形成。PD98059与SB203580在抑制成骨细胞增殖、降低成骨细胞TRPV6 mRNA表达、减少钙结节形成的作用方面存在协同作用。     

Modulation of renal epithelial barrier function by mitogen-activated protein kinases (MAPKs): mechanism of cyclosporine A-induced increase in transepithelial resistance

BACKGROUND: Cyclosporine A (CsA) has been shown to increase transepithelial resistance in Madin-Darby canine kidney (MDCK) cells, and the mechanism may involve altered phosphorylation of junctional proteins. In this study, we examine the effect of the extracellular signal-regulated protein kinase (ERK) 1/2 and p38 mitogen-activated protein kinase (MAPK) pathways on the basal transepithelial resistance (TER) and on the CsA-induced increase in TER across MDCK monolayers. Here we present evidence that CsA may be mediating some of its effects through activation of the ERK 1/2 MAPK pathway. METHODS: MDCK cells were treated with CsA (4.2 micromol/L) and paracellular permeability was assessed by measuring TER. The role of the ERK 1/2 and the p38 MAPK pathways in modulating TER was investigated using the inhibitors PD98059 and U0126 for ERK 1/2 and SB203580 for p38. ERK 1/2 and p38 phosphorylation/activation was also examined by Western blot analysis. RESULTS: CsA (4.2 micromol/L) increased the TER of MDCK monolayers. The ERK 1/2 inhibitor PD98059 decreased basal TER and also ameliorated the CsA-induced increase in TER. Similar results were found with the U0126 inhibitor of ERK 1/2. The p38 inhibitor SB203580 had no effect on the basal TER of the monolayers, however, SB203580 significantly augmented the CsA-induced increase in TER. CsA was shown to significantly activate ERK 1/2 and this activation by CsA was prevented by PD98059. Inhibition of the p38 pathway by SB203580 also resulted in activation of ERK 1/2 and this activation of ERK 1/2 was further enhanced by CsA. No effect of CsA or the inhibitors PD98059 or SB203580 on p38 phosphorylation was detected. CONCLUSION: The results presented here suggest that activation of the ERK 1/2 MAPK cascade is important in the regulation of the paracellular permeability in MDCK cells. Activation of this pathway appears to be pivotal to the CsA-induced increase in TER.     

缺氧时丝裂原激活蛋白激酶类对人肾小管上皮细胞富含半胱氨酸蛋白61基因转录活性的调控

目的 探讨丝裂原激活蛋白激酶类（MAPKs）对缺氧条件下人近端肾小管上皮细胞（HKC）中富含半胱氨酸蛋白61（Cyr61）基因转录活性的调控机制。方法 缺氧培养HKC，Northern印迹检测Cyr61mRNA表达；Western印迹检测Cyr61、p38、细胞外信号调节激酶（ERK1／2）、c—Jun—N末端蛋白激酶（JNK）以及缺氧诱导因子1c（HIF-1α）的表达。构建含有人Cyr61基因启动子的报告基因Cyr61-luc质粒，将其单独或者分别与表达活性MAPKs的质粒Ca—MEK1和Ca—MKK6共同瞬时转染HKC。通过荧光素酶活性检测观察缺氧、MAPKs抑制剂和MAPKs活性酶对Cyr61基因转录活性的调控。结果 缺氧时HKC表达cyr61、HIF-1α增高，ERK1／2、JNK、p38总量不变，而其各自的磷酸化形式均明显增加。HKC转染Cyr—luc后，p38通路抑制剂SB203580和ERK通路抑制剂PD98059显著抑制缺氧时Cyr61的转录活性，两者协同作用时抑制作用显著增强。Ca—MEK1与Cyr—luc共转染HKC后，Cyr61转录活性无改变；而Ca—MKK6与Cyr—luc共转染后，Cyr61转录活性显著增高。对缺氧培养的HKC，PD98059处理使HIF-1α和Cyr61蛋白表达显著降低；SB203580处理可显著降低Cyr61蛋白表达，但对HIF-1α无影响。结论 在HKC中，缺氧可通过p38通路直接上调Cyr61基因启动子活性，也可通过ERK1／2途径促进HIF-1α表达，间接调节Cyr61基因启动子活性。     

Differential Activation of Mitogen-activated Protein Kinases in Ischemic and Anesthetic Preconditioning

Background: Accumulating evidence pinpoints to the pivotal role of mitogen-activated protein kinases (MAPKs) in the signal transduction underlying cardiac preconditioning.

Methods: PD98059, an inhibitor of extracellular signal-regulated protein kinase (MEK-ERK1/2), and SB203580, an inhibitor of p38 MAPK, were used to evaluate the role of MAPKs with respect to postischemic functional recovery in isolated perfused rat hearts subjected to ischemic preconditioning (IPC) and anesthetic preconditioning (APC). Western blot analyses were used to determine the degree of ERK1/2 and p38 MAPK activation after the application of the preconditioning stimulus and after ischemia-reperfusion. Immunohistochemical staining served to visualize subcellular localization of activated MAPKs.

Results: PD98059 and SB203580 abolished postischemic functional recovery in IPC but not in APC. IPC but not APC markedly activated ERK1/2 and p38 MAPK, which were abrogated by coadministration of the specific blockers. Conversely, IPC and APC enhanced ERK1/2 activity after ischemia-reperfusion as compared to nonpreconditioned hearts, and IPC in addition enhanced p38 MAPK activity. Coadministration of PD98059 and SB203580 during IPC but not during APC inhibited postischemically enhanced MAPK activities. Moreover, chelerythrine and 5-hydroxydecanoate, effective blockers of IPC and APC, annihilated IPC- and APC-induced enhanced postischemic responses of MAPKs. Finally, administration of PD98059 during ischemia-reperfusion diminished the protective effects of IPC and APC. Immunohistochemistry revealed increased ERK1/2 activity primarily in intercalated discs and nuclei and increased p38 MAPK activity in the sarcolemma and nuclei of IPC-treated hearts.     

丝裂原活化蛋白激酶类和蛋白激酶C在转化生长因子β1诱导肾小管细胞结缔组织生长因子表达中的作用

目的了解转化生长因子β1（TGF-β1）诱导肾小管细胞结缔组织生长因子（CTGF）表达的机制，特别是蛋白激酶C（PKC）和丝裂原活化蛋白激酶（MAPK）在CTGF基因表达中的作用及其对Smad磷酸化的影响。方法分别应用PKC抑制剂G06850以及MAPK的3个组成成分ERK、JNK和p38MAPK的抑制剂PD98059、U0126、SP600125和SB203580阻断相应通路，观察其对TGF．131诱导的CTGF表达以及Smad2／Smad3磷酸化的影响。结果TGF-β1（5μg／L）以时间依赖方式诱导HK-2细胞中Smad2／Smad3的磷酸化，从基础值0．87±0．09上升至2h时高峰2．350±0.11。PKC抑制剂G06850（5μmol／L）和ERK抑制剂PD98059（10μmol／L）、U0126（10μmol／L）可部分抑制TGF-β1诱导的CTGF表达，而p38MAPK抑制剂SB203580（20μmol／L）和JNK抑制剂SP600125（10μmol／L）对TGF-β1诱导的CTGF的表达无影响。PKC抑制剂G06850（5μmol／L）可减少TGF-β1诱导的Smad2／Smad3磷酸化，而ERK抑制剂PD98059（10μmol／L）和U0126（10μmol／L）对Smad2／Smad3的磷酸化没有影响。结论在肾小管上皮细胞中，TGF-β1诱导CTGF的表达需要PKC和Ras／MEK／ERK的参与。PKC以Smad依赖的方式参与肾小管上皮细胞中TGF-β1诱导的CTGF的表达，而Ras／MEK／ERK对CTGF表达的调节不依赖于Smads。     

Cardiopulmonary bypass reduces peripheral microvascular contractile function by inhibition of mitogen-activated protein kinase activity

BACKGROUND: Mitogen-activated protein kinases (MAPK) have been implicated in pathophysiologic responses to cardiopulmonary bypass (CPB). MAPK are deactivated by phosphatases, such as MAPK phosphatase-1 (MKP-1). We hypothesized that MAPK mediate peripheral microvascular contractile dysfunction caused by CPB in humans. METHODS: Skeletal muscle was harvested before and after CPB. Protein levels of MKP-1 and activated extracellular signal-regulated kinase 1/2 (ERK1/2) and p38 were measured. MKP-1 gene expression was measured. Peripheral microvessel responses to vasopressors were studied by videomicroscopy. Contractile function also was measured after MAPK inhibition with PD98059 (ERK1/2) and SB203580 (p38). ERK1/2, p38, and MKP-1 were localized by immunohistochemistry and in situ hybridization. RESULTS: ERK1/2 and p38 activity was decreased in peripheral tissue after CPB. MKP-1 was increased after CPB. Contractile responses of peripheral arterioles to phenylephrine and vasopressin were decreased after CPB. Microvessel reactivity also was reduced after treatment with PD98059 and SB203580. ERK1/2, p38, and MKP-1 localized to peripheral arterioles in tissue sections. CONCLUSIONS: CPB reduces ERK1/2 and p38 activity in peripheral tissue, potentially by MKP-1. Contractile responses of peripheral arterioles to phenylephrine and vasopressin are dependent on ERK1/2 and p38 and are decreased after CPB. These results suggest that alterations in MAPK pathways in part regulate peripheral microvascular dysfunction after CPB in humans.     

Differential activation of mitogen-activated protein kinases in ischemic and anesthetic preconditioning

BACKGROUND: Accumulating evidence pinpoints to the pivotal role of mitogen-activated protein kinases (MAPKs) in the signal transduction underlying cardiac preconditioning. METHODS: PD98059, an inhibitor of extracellular signal-regulated protein kinase (MEK-ERK1/2), and SB203580, an inhibitor of p38 MAPK, were used to evaluate the role of MAPKs with respect to postischemic functional recovery in isolated perfused rat hearts subjected to ischemic preconditioning (IPC) and anesthetic preconditioning (APC). Western blot analyses were used to determine the degree of ERK1/2 and p38 MAPK activation after the application of the preconditioning stimulus and after ischemia-reperfusion. Immunohistochemical staining served to visualize subcellular localization of activated MAPKs. RESULTS: PD98059 and SB203580 abolished postischemic functional recovery in IPC but not in APC. IPC but not APC markedly activated ERK1/2 and p38 MAPK, which were abrogated by coadministration of the specific blockers. Conversely, IPC and APC enhanced ERK1/2 activity after ischemia-reperfusion as compared to nonpreconditioned hearts, and IPC in addition enhanced p38 MAPK activity. Coadministration of PD98059 and SB203580 during IPC but not during APC inhibited postischemically enhanced MAPK activities. Moreover, chelerythrine and 5-hydroxydecanoate, effective blockers of IPC and APC, annihilated IPC- and APC-induced enhanced postischemic responses of MAPKs. Finally, administration of PD98059 during ischemia-reperfusion diminished the protective effects of IPC and APC. Immunohistochemistry revealed increased ERK1/2 activity primarily in intercalated discs and nuclei and increased p38 MAPK activity in the sarcolemma and nuclei of IPC-treated hearts. CONCLUSIONS: Although MAPKs may orchestrate cardioprotection as triggers and mediators in IPC, they are devoid of triggering, but they may have mediator effects in APC.     

beta1-integrin-ligand disengagement induces in vitro capillary tube disruption mediated by p38 MAPK activity

BACKGROUND: Disrupting cell-matrix interactions may lead to capillary injury as seen in sepsis and transplant rejection. Previously, we demonstrated capillary disruption mediated by beta1-integrin-ligand disengagement. We now determine whether p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK) pathways are involved in this capillary injury. METHODS: Endothelial capillaries on Matrigel were preincubated with a p38 MAPK inhibitor (SB203580), ERK pathway inhibitor (PD98059), or dimethyl sulfoxide. Subsequently, a beta1-integrin blocking (P5D2) or an irrelevant antibody was added. After 24 hours, capillary integrity was quantified as capillary intersections/well. Antibody-treated cell lysates then were immunoprecipitated with either a phospho-p38 MAPK or phospho-ERK1/2 antibody. Kinase activity was measured with ATF-2 and Elk-1 fusion proteins as substrates for p38 MAPK and ERK, respectively, followed by Western blotting. RESULTS: P5D2 disrupted capillary tubes. Increased p38 MAPK activity at 8 hours and ERK activity at 2 and 8 hours were seen in P5D2-treated lysates. Preincubation with SB203580, but not with PD98059 or DSMO, significantly reduced capillary tube disruption. CONCLUSIONS: The beta1-integrin-ligand disengagement resulted in capillary disruption and stimulated p38 MAPK and ERK activity. In spite of activation of both pathways, the p38 MAPK but not the ERK pathway inhibitor prevented beta1-integrin antibody effects. Inhibiting p38 MAPK may mitigate capillary injury associated with sepsis and transplant rejection.     

ERK and p38 MAP kinase are required for rat renal development

BACKGROUND: We previously demonstrated that extracellular signal-regulated protein kinase (ERK) and p38 mitogen-activated protein (MAP) kinase (p38) are strongly expressed in the embryonic kidney. In the present study, we investigated the role of ERK and p38 during kidney development. METHODS: Rat metanephroi were cultured from 15-day-old embryos, and exposed to inhibitors of MEK, an activator of ERK, PD98059 (300 micromol/L), U0126 (10 micromol/L), or a p38 inhibitor SB203580 (30 micromol/L) 24 to 120 hours after the start of culture. Growth of metanephroi was measured by surface area and thymidine incorporation. Ureteric buds and glomeruli were identified by labeling with Dolichos biflorus lectin and peanut agglutinin, respectively. PCNA staining and TUNEL assay were performed on kidney sections. The level of apoptosis was evaluated by examining DNA ladder formation. RESULTS: Growth of metanephroi was significantly inhibited by SB203580 but not by PD98059 or U0126. Ureteric bud branching was not affected by SB203580 or MEK inhibitors. Glomerular number was markedly reduced by SB203580 and to a lesser extent by U0126 (14 +/- 2 and 48 +/- 10% of controls, respectively). On histological examination, the number of tubuloglomerular structures was reduced in MEK inhibitor-treated metanephroi compared to controls. Very few mesenchymal condensates were observed in kidneys incubated with SB203580. PCNA-positive cells were reduced in SB203580-treated metanephroi compared to control and PD98059-treated kidneys. Apoptosis was increased in SB203580-treated kidneys and to a lesser extent in PD98059-treated cultures. CONCLUSIONS: Both ERK and p38 are required for renal development. ERK appears to play a role in nephrogenesis and p38 for kidney growth and nephrogenesis.     

Sphingosine-1-phosphate-induced smooth muscle cell migration involves the mammalian target of rapamycin

BACKGROUND: Vascular smooth muscle cell (SMC) migration is an important component of the development of intimal hyperplasia. Sphingosine-1-phosphate (S-1-P) is a lipid released from activated platelets with numerous cellular effects including the stimulation of SMC migration in vitro. We examined the role of the mammalian target of rapamycin and ribosomal p70S6 kinase (p70S6K) in S-1-P-induced SMC migration . METHODS: Rat arterial SMCs were cultured in vitro. Linear wound and Boyden microchemotaxis assays of migration were performed in the presence of S-1-P (0.01 to 100 micromol/L) with and without rapamycin (10 nmol/L). Western blotting was performed for phosphorylated and total p70S6K, ERK1/2, and p38(MAPK) after stimulation with S-1-P (0.1 micromol/L), with and without rapamycin pretreatment. Phosphorylation of p70S6K was also assayed after S-1-P treatment in the presence and absence of inhibitors of PI3 kinase (wortmannin, WN, and LY294002, LY), Akt (AktI), p38(MAPK) (SB203580), and MEK1 (PD98059). RESULTS: S-1-P stimulated migration of SMCs in both linear wound and Boyden chamber assays compared to control (P < .05); these responses were inhibited by rapamycin to below the level of control (P < .05 vs S-1-P alone for both assays) in a dose-dependent manner (inhibitory concentration of 50%, 10 nmol/L). S-1-P stimulated phosphorylation of ERK1/2, p38(MAPK), and p70S6K, which peaked at 5 minutes for ERK1/2 and p38(MAPK) and10 minutes for p70S6K (2-fold increase over control for each, P < .05). Rapamycin prevented the phosphorylation of p70S6K at the Thr 389 site (which correlates with enzyme activity), reduced ERK1/2 phosphorylation, but had no effect on the Thr 421/Ser 424 site or on p38(MAPK) phosphorylation. Wortmannin and LY294002 inhibited phosphorylation of the Thr 389 site of p70S6K. AktI and SB203580 had no effect on p70S6K, whereas PD98059 had a marginal effect. CONCLUSIONS: S-1-P-induced SMC migration was completely inhibited by rapamycin, indicating that the p70S6K pathway is involved. This mechanism likely involves modulation of the ERK1/2 pathway. S-1-P stimulates phosphorylation of p70S6K in a MEK1-dependent, PI3 kinase-dependent, but Akt-independent manner.     

Immune suppression in polymicrobial sepsis: differential regulation of Th1 and Th2 responses by p38 MAPK

BACKGROUND: Studies have indicated that a shift from a Th1 to a Th2 response occurs that contributes to the late immunosuppression seen during sepsis. However, the mechanism by which this occurs is unknown. In this regard, mediators released in response to sepsis are thought to upregulate a family of stress-induced mitogen-activated protein kinases (MAPKs), such as JNK, ERK, and p38 MAPK, which may play a role in this process. MATERIALS AND METHODS: To determine the role of MAPK in immune suppression, we induced polymicrobial sepsis in C3H/HeN male mice using cecal ligation and puncture (CLP). Splenic lymphocytes were harvested 24 h post-CLP and stimulated with the T-cell mitogen concanavalin A, and the expression and activation of these MAPKs were assessed by Western analysis. To determine the extent to which these MAPKs may have an impact on splenic immune function, cells were pretreated with a 10 microM concentration of the p38 MAPK inhibitor SB203580 or the MEK inhibitor PD98059 or with DMSO vehicle. The cells were then stimulated with 2.5 microg/ml of the T-cell mitogen concanavalin A, and cytokine release was then determined (by ELISA). RESULTS: In the lymphocytes from CLP mice no JNK signal was detected, however, p38 expression and activation were markedly (P < 0.05, n = 6) increased. In contrast, the expression of activated ERK markedly decreased following septic challenge. The results indicate that p38 MAPK inhibition with SB203580 suppressed the sepsis-induced augmentation of interleukin-10 release while restoring the suppressed Th1 cytokine interleukin-2 release typically encountered following sepsis. Inhibition of ERK had no effect on cytokine release. Neither PD98059 nor SB203580 had an effect on interferon gamma release or on proliferative capacity. CONCLUSION: This would indicate that the induction of p38 MAPK activation in splenocytes contributes to the immunosuppression seen in late sepsis.