沥水调脂胶囊对轻度修饰低密度脂蛋白诱导的血管平滑肌细胞单核细胞趋化因子1及内皮细胞P选择素表达的影响

探讨健脾祛痰化瘀方药(沥水调脂胶囊)含药血清对轻度修饰低密度脂蛋白诱导的血管平滑肌细胞表达单核细胞趋化因子1及内皮细胞表达P选择素的影响。用细胞酶联免疫法测定内皮细胞P选择素的表达，酶联免疫法测定培养血管平滑肌细胞上清液中单核细胞趋化因子1的含量。结果发现，20％沥水调脂胶囊除蛋白含药血清组对轻度修饰低密度脂蛋白诱导的血管平滑肌细胞单核细胞趋化因子1表达的升高具有一定的抑制作用。10％含药血清组对轻度修饰低密度脂蛋白诱导的内皮细胞表达P选择素已具有抑制作用，当含药血清浓度达20％时其抑制作用更为明显。由此可见，通过抑制细胞炎性因子单核细胞趋化因子1和血小板活化因子P选择素，减轻血管炎性反应和血栓形成，是健脾祛痰化瘀方药沥水调脂胶囊抗氧化损伤、防治动脉粥样硬化发生发展及痰瘀互结的机制之一。     

沥水调脂胶囊对弱氧化低密度脂蛋白诱导的血管平滑肌细胞单核细胞趋化蛋白1及血管内皮细胞P选择素表达的影响

目的　通过探讨健脾祛痰方药沥水调脂胶囊含药血清对弱氧化低密度脂蛋白诱导的血管平滑肌细胞表达的单核细胞趋化蛋白 1及血管内皮细胞表达P选择素的影响 ,阐明沥水调脂胶囊抗炎防治动脉粥样硬化作用机理。方法　 1.脐静脉内皮细胞的培养 :取新鲜脐带 ,用Ⅱ型胶原酶消化脐静脉内皮细胞后 ,用含有 2 0 %的胎牛血清的M199培养基接种。实验用第 3代。 2 .脐动脉平滑肌细胞的培养 :取新鲜脐带 ,剥离出脐动脉 ,用Ⅳ型胶原酶联合胰酶 ,分二步消化 ,用 2 0 %的胎牛血清的DMEM培养基接种 ,实验用第 3代 ,实验时用无血清培养基。 3.弱氧化低密度脂蛋白的制备 :用铜离子体外氧化法获得 ,用硫代巴比妥法测硫代巴比妥酸反应物值及琼脂糖电泳 ,测定氧化程度。 4 .含药血清的制备 :用沥水调脂胶囊按成人剂量的 8倍 ,灌喂大鼠 ,取大鼠血清 ,用或不用甲醇沉降蛋白后用冻干机冻干 ,临用时用三蒸水将其稀释至用蛋白沉降前的原体积或血清原体积。 5 .用细胞酶联免疫法测定内皮细胞表面P选择素的表达或酶联免疫法测定平滑肌细胞培养上清液中单核细胞趋化蛋白 1的含量。结果　含 2 0 %的除蛋白含药血清对弱氧化低密度脂蛋白诱导的血管平滑肌细胞表达的单核细胞趋化蛋白 1具有一定的抑制作用。含有 10 %沥水调脂胶囊药血清培养     

健脾祛痰化瘀方对氧化型低密度脂蛋白诱导血管细胞信号分子钙离子和蛋白激酶C表达的影响

为了探讨健脾祛痰化瘀方在抗氧化型低密度脂蛋白致动脉粥样硬化中对信号转导分子钙离子和蛋白激酶C的影响，分别以健脾祛痰化瘀方-沥水调脂胶囊含药血清(浓度分别为5％、10％和20％)、氧化型低密度脂蛋白(100mg／L)处理人脐静脉内皮细胞和人脐动脉平滑肌细胞，以流式细胞仪检测两种细胞胞质游离钙离子浓度，以液体闪烁仪检测平滑肌细胞胞膜蛋白激酶C活性。结果发现，沥水调脂胶囊含药血清对氧化型低密度脂蛋白引起的内皮细胞、平滑肌细胞胞质游离钙离子浓度升高及平滑肌细胞胞膜蛋白激酶C活性升高有明显的抑制作用，其中20％含药血清作用最为明显。结果提示，健脾祛痰化瘀方可能通过调节钙离子、蛋白激酶C两种信号传递分子的变化起抗氧化作用，进而抑制内皮细胞凋亡及平滑肌细胞增殖，达到阻止动脉粥样硬化发生的作用。     

线粒体融合素2基因突变体对大鼠血管平滑肌细胞增殖的影响

目的 研究大鼠线粒体融合素2基因的蛋白激酶A磷酸化位点两种突变体对大鼠血管平滑肌细胞增殖的影响及其相关的信号通路.方法 利用两种携带蛋白激酶A磷酸化位点突变的线粒体融合素2基因重组腺病毒(Adv-Mfn2-alaPKA和Adv-Mfn2-asnPKA)和携带线粒体融合素2基因的重组腺病毒(Adv-Mfn2),感染培养的大鼠血管平滑肌细胞.水溶性四甲基偶氮唑盐法比较各组细胞增殖的变化;流式细胞术比较各组细胞周期的变化;免疫印迹法比较各组线粒体融合素2基因和磷酸化细胞外调节激酶1/2蛋白表达变化.结果 感染重组腺病毒的三组细胞线粒体融合素2基因表达差异无显著性.与对照组相比,Adv-Mfn2-alaPKA和Adv-Mfn2组显著抑制细胞增殖(P<0.01),停滞于G_0/G_1期细胞比例显著增加(P<0.01),磷酸化细胞外调节激酶1/2蛋白表达水平显著降低(P<0.01),且Adv-Mfn2-slaPKA作用更明显(P<0.01),而Adv-Mfn2-asnPKA组较对照组差异无显著性.结论 Mfn2-alaPKA通过细胞外调节激酶1/2信号通路抑制大鼠血管平滑肌细胞增殖的作用较线粒体融合素2基因更明显;而Mfn2-asnPKA对血管平滑肌细胞无抑制增殖的作用,对细胞外调节激酶1/2信号通路也无作用.蛋白激酶A磷酸化位点是调控线粒体融合素2基因抗血管平滑肌细胞增殖的重要功能位点.     

热休克蛋白90对氧化应激激活的大鼠血管平滑肌细胞细胞外信号调节激酶的作用

目的探讨热休克蛋白90对氧化应激激活的细胞外信号调节激酶的作用。方法取SD雄性大鼠胸主动脉做原代平滑肌细胞培养。用1μmol/L可溶性鸟苷酰环化酶抑制剂6-Anilinoquinoline-5,8-quinolinedione(LY83583)处理4~12代大鼠血管平滑肌细胞不同时间,蛋白免疫印迹检测细胞内热休克蛋白90、磷酸化和未磷酸化细胞外信号调节激酶1/2。用格尔德霉素(热休克蛋白90的特异性阻断剂)预处理细胞30 min,再用LY83583处理120 min,免疫共沉淀和蛋白免疫印迹检测热休克蛋白90与细胞外信号调节激酶及磷酸化的细胞外信号调节激酶的结合,免疫荧光检测细胞核内磷酸化的细胞外信号调节激酶。结果LY83583处理120 min时细胞内热休克蛋白90表达达高峰,较0 min时增加9倍,与细胞外信号调节激酶1/2的第二个活化高峰一致。LY83583处理血管平滑肌细胞120 min后,热休克蛋白90与磷酸化的细胞外信号调节激酶1/2结合较对照组升高了5.5倍(P<0.01),磷酸化的细胞外信号调节激酶1/2的量增加了6.1倍(P<0.01),而细胞核内的磷酸化的细胞外信号调节激酶1/2也明显增加;5μmol/L格尔德霉素预处理后,LY83583的这些效应则被阻断。结论氧化应激增加大鼠血管平滑肌细胞内热休克蛋白90,并增加其与细胞外信号调节激酶1/2及磷酸化的细胞外信号调节激酶1/2的结合,促进磷酸化的细胞外信号调节激酶1/2核转位。这可能是氧化应激激活大鼠中膜血管平滑肌细胞内细胞外信号调节激酶1/2信号通路活性的重要机制之一,为抗氧化应激引起的血管中膜平滑肌细胞增殖提供新的分子靶点。     

白细胞介素10抑制大鼠血管平滑肌细胞增殖的信号途径

为探讨白细胞介素 10抑制血管紧张素Ⅱ诱导的大鼠血管平滑肌细胞增殖的细胞信号机制 ,采用3 H -TdR掺入的方法检测血管平滑肌细胞DNA合成 ,3 2 P ATP掺入检测丝裂素活化蛋白激酶和蛋白激酶C活性 ,蛋白免疫印迹杂交及免疫沉淀方法检测粘着斑激酶蛋白表达及其活性变化。结果显示 ,白细胞介素 10呈浓度依赖性抑制血管紧张素Ⅱ诱导的血管平滑肌细胞增殖 ,同时下调血管紧张素Ⅱ引起的丝裂素活化蛋白激酶、蛋白激酶C和粘着斑激酶信号的激活 (P <0 .0 5或P <0 .0 1)。因此白细胞介素 10可能通过下调血管紧张素Ⅱ刺激的丝裂素活化蛋白激酶、蛋白激酶C和粘着斑激酶等增殖相关信号的激活而抑制其刺激的血管平滑肌细胞增殖     

氧化型低密度脂蛋白对血管平滑肌细胞小凹蛋白1表达的抑制作用及其与信号调节激酶的关系

目的 观察氧化型低密度脂蛋白对血管平滑肌细胞小凹蛋白1表达的抑制作用及其与细胞外信号调节激酶活性的关系.方法 50 mg/L 氧化型低密度脂蛋白处理血管平滑肌细胞不同时间,或同时加入25 μmol/L细胞外信号调节激酶信号通路的特异性阻断剂,Western 印迹检测血管平滑肌细胞小凹蛋白1和细胞外信号调节激酶的变化.结果 50 mg/L氧化型低密度脂蛋白作用细胞24 h后小凹蛋白1的表达明显下降,细胞外信号调节激酶磷酸化活性显著增高,阻断氧化型低密度脂蛋白对细胞外信号调节激酶的激活可显著促进小凹蛋白1的表达.结论 血管平滑肌细胞源性泡沫细胞小凹蛋白1的表达下调与氧化型低密度脂蛋白激活细胞外信号调节激酶及其介导的信号传导密切相关.     

降钙素基因相关肽抑制血管平滑肌细胞能量代谢的AMP激活蛋白激酶信号通路

目的观察降钙素基因相关肽对血管紧张素Ⅱ诱导血管平滑肌细胞增殖过程中能量代谢的影响及机制,探索细胞外信号调节激酶和AMP激活蛋白激酶相关信号蛋白在该作用中的地位。方法组织贴块法体外培养SD大鼠胸主动脉血管平滑肌细胞,取第3～10代用于实验。分别用降钙素基因相关肽或/和血管紧张素Ⅱ处理细胞。MTT法及细胞计数法观察降钙素基因相关肽对血管紧张素Ⅱ诱导大鼠血管平滑肌细胞增殖的影响;詹纳斯绿B染色观察细胞线粒体形态及体积;ATP检测试剂盒检测细胞内ATP水平;Western Blotting检测细胞磷酸化AMP激活蛋白激酶的表达。结果降钙素基因相关肽预处理能降低血管紧张素Ⅱ诱导的大鼠血管平滑肌细胞的增殖(P<0.05),同时拮抗血管紧张素Ⅱ引起细胞内线粒体肿胀、ATP水平升高,在此过程中伴随细胞内磷酸化AMP激活蛋白激酶表达下调(P<0.05);降钙素基因相关肽受体拮抗剂CGRP8-37能拮抗降钙素基因相关肽对血管紧张素Ⅱ促增殖和促代谢的抑制作用(P<0.05);细胞外信号调节激酶抑制剂PD98059能部分拮抗降钙素基因相关肽对磷酸化AMP激活蛋白激酶的抑制作用(P<0.05)。结论降钙素基因相关肽能显著抑制血管紧张素Ⅱ诱导大鼠血管平滑肌细胞增殖过程中的能量代谢,其细胞内信号通路可能涉及到降钙素基因相关肽/降钙素基因相关肽1型受体-丝裂原细胞外激酶/细胞外信号调节激酶-磷酸化AMP激活蛋白激酶信息传递链。     

小凹蛋白1-小凹在血管紧张素Ⅱ诱导血管平滑肌细胞增殖信号转导通路中的作用

为观察小凹蛋白1和小凹对血管紧张素Ⅱ诱导血管平滑肌细胞增殖信号转导通路的调控作用，本文用Westem Blot、小凹蛋白1反义寡核苷酸技术及氚标胸腺嘧啶脱氧核苷掺入法观察到血管紧张素Ⅱ刺激细胞外信号调节激酶活化和血管平滑肌细胞增殖，同时抑制小凹蛋白1表达。小凹蛋白1反义寡核苷酸处理可增强血管紧张素Ⅱ激活细胞外信号调节激酶和刺激血管平滑肌细胞增殖的作用。细胞外信号调节激酶抑制剂PD98059和小凹结构抑制剂制霉菌素均可阻断血管紧张素Ⅱ所致细胞外信号调节激酶的活化和小凹蛋白1表达下降和细胞增殖。     

钙激动剂介导血管平滑肌细胞增殖的信号转导途径

为探讨钙调神经磷酸酶依赖的信号通路在雷尼丁刺激的大鼠血管平滑肌细胞增殖中的作用，以培养的大鼠血管平滑肌细胞为模型，用雷尼丁刺激其内贮Ca^2 释放入胞浆，环孢素A阻断钙调神经磷酸酶信号通路，维拉帕米阻断钙通道，检测血管平滑肌细胞钙调神经磷酸酶、丝裂素活化蛋白激酶和蛋白激酶C活性，用^3H-亮氨酸及^3H－胸腺嘧啶掺入量作为反应细胞增殖的指标。结果显示，雷尼丁刺激组蛋白核酸合成速率明显增高，与对照组相比差异显著（P＜0．01）；环孢素A及维拉帕米能明显抑制雷尼丁介导的平滑肌细胞蛋白核酸合成速率增高，与雷尼丁刺激组相比差异显著（P＜0．01）。同时发现雷尼丁刺激组钙神经磷酸酶、蛋白激酶C活性与对照组平滑肌细胞相比差异显著（P＜0．05或0．01）。环孢素A和维拉帕米抑制雷尼丁介导的平滑肌细胞钙调神经磷酸酶活性增高，维拉帕米抑制雷尼丁介导的平滑肌细胞蛋白激酶C活性的增高。提示钙调神经磷酸酶信号通路在雷尼丁刺激的平滑肌细胞增殖中起重要作用，但钙调神经磷酸酶信号通路不是雷尼丁介导平滑肌细胞增殖的唯一信号通路，以丝裂素活化蛋白激酶为核心的信号通路亦参与了雷尼丁刺激的平滑肌细胞增殖。     

Increased JNK, AP-1 and NF-kappa B DNA binding activities in isoproterenol-induced cardiac remodeling

The in vivo signal transduction pathway, responsible for isoproterenol-induced cardiac hypertrophy or remodeling, remains to be clarified. The purpose of this study was to examine c-Jun NH2-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK), activator protein-1 (AP-1) and nuclear factor-kappa B (NK-kappa B) DNA binding activity, which seem to be important in a signal transduction cascade upstream of the increased level of mRNA expression observed in isoproterenol-induced cardiac remodeling. Rats were continuously infused with saline and isoproterenol by intravenous injection (a short period; 0.5 microgram/kg/min) and an osmotic minipump (a long period; 0.5 or 3 mg/kg/day). Cardiac morphology was measured by echocardiography. JNK and ERK were measured by in gel kinase assay. AP-1 and NF-kappa B DNA binding activity was determined using an electrophoretic mobility shift assay. Echocardiogram showed that the thickness of the left ventricular anterior wall (AW) and left ventricular posterior wall (PW) increased at day 1 in low doses, and at day 1 in high doses. Isoproterenol significantly increased ERK and JNK activity at 15 min after intravenous infusion of 0.5 microgram/kg/min isoproterenol. At late phase about JNK and ERK activity, only a high dose of isoproterenol increased JNK. AP-1 DNA binding activities spurred by low or high doses of isoproterenol administration increased at 12 h, reached their peak of 24.1- and 37.1-fold (P < 0.01), respectively, at 24 h, and thereafter decreased. Although low doses of isoproterenol did not change the level of NF-kappa B DNA binding activities, high doses increased it to 10.9-fold (P < 0.01) at day 2. This study showed increased JNK, ERK, AP-1 and NF-kappa B DNA binding activities in isoproterenol-induced cardiac remodeling. AP-1 may contribute to the isoproterenol-induced cardiac remodeling, and JNK or NF-kappa B may also play some roles in it.     

Deletion of the loop region of Bcl-2 completely blocks paclitaxel-induced apoptosis

At high concentrations, the tubule poison paclitaxel is able to kill cancer cells that express Bcl-2; it inhibits the antiapoptotic activity of Bcl-2 by inducing its phosphorylation. To localize the site on Bcl-2 regulated by phosphorylation, mutant forms of Bcl-2 were constructed. Mutant forms of Bcl-2 with an alteration in serine at amino acid 70 (S70A) or with deletion of a 60-aa loop region between the alpha1 and alpha2 helices (Deltaloop Bcl-2, which also deletes amino acid 70) were unable to be phosphorylated by paclitaxel treatment of MDA-MB-231 cells into which the genes for the mutant proteins were transfected. The Deltaloop mutant completely inhibited paclitaxel-induced apoptosis. In cells expressing the S70A mutant, paclitaxel induced about one-third the level of apoptosis seen with wild-type Bcl-2. To evaluate the role of mitogen-activated protein kinases (MAPKs) in Bcl-2 phosphorylation, the activation of c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and p38 was examined. Paclitaxel-induced apoptosis was associated with phosphorylation of Bcl-2 and activation of ERK and JNK MAPKs. If JNK activation was blocked by transfections with either a stress-activated protein kinase kinase dominant-negative (K-->R) gene (which prevents the activation of a kinase upstream of JNK) or MAPK phosphatase-1 gene (which dephosphorylates and inactivates JNK), Bcl-2 phosphorylation did not occur, and the cells were not killed by paclitaxel. By contrast, neither an ERK inhibitor (PD098059) nor p38 inhibitors (SB203580 and SB202190) had an effect on Bcl-2 phosphorylation. Thus, our data show that the antiapoptotic effects of Bcl-2 can be overcome by phosphorylation of Ser-70; forms of Bcl-2 lacking the loop region are much more effective at preventing apoptosis than wild-type Bcl-2 because they cannot be phosphorylated. JNK, but not ERK or p38 MAPK, appear to be involved in the phosphorylation of Bcl-2 induced by paclitaxel.     

Adenovirus-mediated overexpression of catalase attenuates oxLDL-induced apoptosis in human aortic endothelial cells via AP-1 and C-Jun N-terminal kinase/extracellular signal-regulated kinase mitogen-activated protein kinase pathways

In a variety of vascular disorders, endothelial cells (ECs) are exposed to high levels of reactive oxygen species (ROS) generated intercellularly. Recently, several anti-oxidants, including catalase, have been suggested to be cytoprotective against the development of atherosclerosis. The object of this study was to investigate whether adenovirus-mediated gene transfer of catalase in ECs can attenuate ROS production and cell apoptosis under oxidized low density lipoprotein (oxLDL) stimulation. Adenovirus-mediated gene transfer of human catalase gene (Ad-Cat) resulted in a high level of catalase overexpression in human arterial EC (HAEC), which manifested a time-dependent increase in cell viability under the exposure of oxLDL and decreased oxLDL-induced apoptosis. Phosphorylation studies of ERK1/2, JNK, and p38, three subgroups of mitogen activator protein kinase demonstrated that catalase overexpression suppressed JNK phosphorylation and increased ERK1/2 phosphorylation. NF-kappaB and AP-1 were induced after the exposure of HAECs to oxLDL. While catalase overexpression was found to inactivate AP-1, it had no effect on NF-kappaB activity. These results provide the evidence that overexpression of catalase in ECs attenuates ROS production and cell apoptosis under oxLDL stimulation. The protective effect is mediated through the downregulation of JNK and the upregulation of ERK1/2 phosphorylation as well as AP-1 inactivation. This observation supports the feasibility of catalase gene transfer to human endothelium to protect against oxidant injury.     

PTH regulation of c-Jun terminal kinase and p38 MAPK cascades in intestinal cells from young and aged rats

In the present study, we examined the role of Parathyroid hormone (PTH) on the c-Jun N-terminal kinase (JNK) 1/2 and p38 mitogen-activated protein kinase (MAPK) members of the MAPK family as it relates to ageing by measuring hormone-induced changes in their activity in enterocytes isolated from young (3 month old) and aged (24 month old) rats. Our results show that PTH induces a transient activation of JNK 1/2, peaking at 1 min (+threefold). The hormone also stimulates JNK 1/2 tyrosine phosphorylation, in a dose-dependent fashion, this effect being maximal at 10 nM. PTH-induced JNK 1/2 phosphorylation was suppressed by its selective inhibitor SP600125. Moreover, hormone-dependent activation of JNK 1/2 was dependent on calcium, since pretreatment of cells with BAPTA-AM or EGTA blocked PTH effects. With ageing, the response to PTH was significantly reduced. JNK basal protein expression was not different in the enterocytes from young and aged rats, however, basal protein phosphorylation increased with ageing. PTH did not stimulate, within 1–10 min, the basal activity and phosphorylation of p38 MAPK in rat intestinal cells. The hormone increased enterocyte DNA synthesis; the response was dose-dependent and decreased (-40%) with ageing. In agreement with the mitogenic role of the MAPK cascades, this effect was blocked by specific inhibitors of extracellular signal-regulated protein kinase (ERK) 1/2 and JNK 1/2. The results obtained in this work expand our knowledge on the mechanism of action of PTH in duodenal cells.     

Cisplatin regulates Sertoli cell expression of transferrin and interleukins

It is well known that exposure to cis-diaminedichloroplatinum (CDDP) results in impairment of spermatogenesis; however, little is known about the signal mechanisms involved in CDDP regulation of Sertoli cell (SC) function. This study was designed to evaluate how CDDP regulates SC signal molecules and mechanisms. Purified rat SC was cultured under serum-free conditions and treated with CDDP (10 ng/ml) at various time points. Western blot analysis was used to determine the activation of extracellular signal-related kinases 1 and 2 (ERK1/2), p38 mitogen-activated protein kinase (MAPK), cJun-N-terminal kinase (JNK), cyclooxygenase (COX)-1 and COX-2, inducible and endothelial nitric oxide synthase (iNOS and eNOS). The levels of transferrin (TF) and prostaglandin (PG)E2, PGF2alpha, PGD2, carbaprostacyclin (cPGI2 analog) in culture medium were quantified by ELISA. Nitrite (NO2(-)) and nitrate (NO3(-)) in culture medium were also quantified by Griess assay. Interleukin (IL)-1beta and IL-6 mRNAs were measured by quantitative real-time PCR (QRT-PCR) analysis. CDDP activated the phosphorylation of ERK1/2 (p-ERK1/2) in the early phase (within 5 min) and the level of transferrin (TF) fell significantly. In addition, CDDP significantly increased the level of COX-2, PGs, and ILs in the late phase (within 24h). When ERK activity inhibitor (PD98059, 10 microM) or COX-2 activity inhibitor (NS-398, 10 microM) was used, CDDP reduction of TF and induction of PG and IL expression were prevented, suggesting that the detrimental effects on spermatogenesis through the impairment of SC induced by CDDP are mediated by the activation of ERK1/2 and COX-2 pathways in SC.     

Preptin对人成骨细胞增殖和分化的影响及机制研究

目的 探讨preptin对人成骨细胞增殖和分化的影响及其信号途径.方法 体外培养人成骨细胞,用10-10、10-9、10-8和10-7mol/L preptin干预24 h,以[3H]脱氧胸腺嘧啶苷掺入法分析细胞增殖,用分光光度计法测定细胞碱性磷酸酶(ALP)活性判断细胞分化程度.Western印迹法检测细胞外信号调节激酶(ERK)、p38丝裂原活化蛋白激酶(p38MAPK)和c-Jun氨基末端激酶(JNK)的磷酸化水平.并在preptin干预前以ERK抑制剂(PD98059)、p38 MAPK抑制剂(SB203580)和JNK抑制剂(SP600125)预处理,观察preptin诱导人成骨细胞增殖和分化的途径.结果 Preptin剂量依赖地增加人成骨细胞的增殖和ALP活性,10-9mol/L浓度时达最大效应(均P<0.01).Preptin刺激人成骨细胞ERK的磷酸化,对p38MAPK和JNK无作用.PD98059阻断preptin刺激的成骨细胞增殖及ALP活性增加(均P<0.05),而SP600125和SB203580无此效应.结论 Preptin通过ERK途径促进人成骨细胞的增殖和分化.     

Activation of mitogen-activated protein kinases in in vivo ischemia/reperfused myocardium in rats.

In this study, we investigate the in vivo activation of mitogen-activated protein kinases (MAPK) as important signal transduction cascades observed after myocardial ischemia/reperfusion. Myocardial continuous ischemia and ischemia/reperfusion was produced in Wistar rats. The activities of MAPKs in the ischemic and ischemia/reperfused regions were measured using an in-gel kinase assay, an in vitro kinase assay and Western blot analysis. Activator protein-1 (AP-1) DNA binding activity was determined using an electrophoretic mobility shift assay. DNA fragmentation was detected as DNA ladders by agarose gel electrophoresis. The p46JNK and p55JNK activities of continuous ischemia were significantly increased at 30 min (5.9 and 4.2 fold, respectively P<0.05). Coronary reperfusion increased both p42ERK and p44ERK activities at 30 min (3.0 and 2.3 fold P<0.01), and both p46JNK and p55JNK activities at 30 min (1.4 and 1.7 fold P<0.05). The AP-1 DNA binding activities of continuous ischemia were significantly increased at 1, 3 and 7 days (28, 21 and 17 fold, respectively P<0.01). Coronary reperfusion markedly decreased AP-1 DNA binding activities at 1 (41%P<0.01) and 3 days (48%P<0.05). Myocardial DNA fragmentation was considerably more enhanced by reperfusion than continuous ischemia. In conclusion, our present work provides the first in vivo evidence that ERK and JNK are activated by reperfusion from the activities of continuous ischemia. These signal transduction mechanisms may be partially responsible for the myocardial injury.     

Insulin-like growth factor I activates c-Jun N-terminal kinase in MCF-7 breast cancer cells

Insulin-like growth factor I (IGF-I) is an important mediator of breast cancer cell growth, although the signaling pathways important for IGF-I-mediated effects in breast cancer cells are still being elucidated. We had demonstrated previously that increased intracellular cAMP in MCF-7 breast cancer cells inhibited cell growth and IGF-I-induced gene expression, as determined using a reporter gene assay. This effect of cAMP on IGF-I signaling was independent of IGF-I-induced activation of the mitogen-activated protein kinases extracellular signal-regulated kinases 1 and 2 (ERK1 and -2). To determine whether this effect of cAMP may be mediated via another mitogen-activated protein kinase, the ability of IGF-I to activate the c-Jun N-terminal kinases (JNKs) was investigated. Treatment of MCF-7 cells with 100 ng/ml IGF-I increased the level of phosphorylated JNK, as determined by Western blot analysis. JNK phosphorylation was not evident until 15 min after treatment with IGF-I, and peak levels of phosphorylation were present at 30-60 min. This was in contrast to ERK phosphorylation, which was present within 7.5 min of IGF-I treatment. Determination of JNK activity using an immune complex assay demonstrated a 3.3- and 3.5-fold increase in JNK1 and -2 activity, respectively, 30 min after treatment with 100 ng/ml IGF-I. The use of PD98059, which inhibits activation of ERK1 and -2, and LY 294002, an inhibitor of phosphatidylinositol 3-kinase, demonstrated that IGF-I-induced activation of JNK1 is independent of ERK and phosphatidylinositol 3-kinase activation. In contrast, increasing intracellular cAMP with forskolin resulted in abrogation of IGF-I-induced JNK activity. In summary, these data demonstrate that IGF-I activates the JNKs in MCF-7 breast cancer cells and, taken together with the results of our previous study, suggest that JNK may contribute to IGF-I-mediated gene expression and, possibly, cell growth in MCF-7 breast cancer cells.     

C-reactive protein induces phosphorylation of insulin receptor substrate-1 on Ser<Superscript>307</Superscript> and Ser<Superscript>612</Superscript> in L6 myocytes,thereby impairing the insulin signalling pathway that promotes glucose transport

Aims/hypothesis C-reactive protein (CRP) is associated with insulin resistance and predicts development of type 2 diabetes. However, it is unknown whether CRP directly affects insulin signalling action. To this aim, we determined the effects of human recombinant CRP (hrCRP) on insulin signalling involved in glucose transport in L6 myotubes. Materials and methods L6 myotubes were exposed to endotoxin-free hrCRP and insulin-stimulated activation of signal molecules, glucose uptake and glycogen synthesis were assessed. Results We found that hrCRP stimulates both c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK)1/2 activity. These effects were paralleled by a concomitant increase in IRS-1 phosphorylation at Ser³⁰⁷ and Ser⁶¹², respectively. The stimulatory effects of hrCRP on IRS-1 phosphorylation at Ser³⁰⁷ and Ser⁶¹² were partially reversed by treatment with specific JNK and ERK1/2 inhibitors, respectively. Exposure of L6 myotubes to hrCRP reduced insulin-stimulated phosphorylation of IRS-1 at Tyr⁶³², a site essential for engaging p85 subunit of phosphatidylinositol-3 kinase (PI-3K), protein kinase B (Akt) activation and glycogen synthase kinase-3 (GSK-3) phosphorylation. These events were accompanied by a decrease in insulin-stimulated glucose transporter (GLUT) 4 translocation to the plasma membrane, glucose uptake and glucose incorporation into glycogen. The inhibitory effects of hrCRP on insulin signalling and insulin-stimulated GLUT4 translocation were reversed by treatment with JNK inhibitor I and the mitogen-activated protein kinase inhibitor, PD98059. Conclusions/interpretation Our data suggest that hrCRP may cause insulin resistance by increasing IRS-1 phosphorylation at Ser³⁰⁷ and Ser⁶¹² via JNK and ERK1/2, respectively, leading to impaired insulin-stimulated glucose uptake, GLUT4 translocation, and glycogen synthesis mediated by the IRS-1/PI-3K/Akt/GSK-3 pathway.