JNK信号通路对NaAsO2诱导NIH3T3细胞中hnRNP K蛋白聚集体形成的影响

 目的：观察核不均一核糖核蛋白(hnRNP)K的表达与定位以及亚砷酸钠（NaAsO2）刺激NIH3T3细胞的反应情况及氧化应激变化,探讨JNK信号通路在hnRNP K蛋白聚集体形成中的作用。方法：构建重组载体pcDNA3-hnRNP K-HA,转染NIH3T3细胞,荧光显微镜观察内源性hnRNP K在细胞中的表达与定位,以及在NaAsO2不同刺激时间该蛋白聚集体的形成情况,并利用活性氧（ROS）检测试剂盒测定胞内ROS水平;给予JNK、MEK、PI3K/Akt、NF-κB和核转运等5种信号通路的抑制剂预处理后,观察聚集体的变化情况。结果：重组质粒构建正确,荧光显微镜观察显示hnRNP K主要定位于胞核中,而重组质粒转染NIH3T3细胞后,可见胞内有蛋白聚集体形成并随NaAsO2刺激时间的延长而递增,且过表达hnRNP K可抑制NaAsO2刺激细胞生成ROS;JNK信号通路抑制剂SP600125明显抑制聚集体的形成。结论：hnRNP K主要定位在NIH3T3细胞的胞核中,胞浆少量分布;NaAsO2可诱导NIH3T3细胞形成hnRNP K蛋白聚集体,此聚集体可抑制胞内ROS生成,且该聚集体的形成有赖于JNK介导的信号通路。     

ERK和P38MAPK升高MLC20磷酸化调节大鼠平滑肌低氧反应性

目的 研究丝裂原活化蛋白激酶(MAPK)亚类ERK、P38 MAPK和JNK在低氧血管平滑肌收缩反应性调节中的作用,并从肌球蛋白轻链(MLC20)磷酸化的钙敏感性调节途径上初步探讨其机制.方法 用低氧培养血管平滑肌细胞(VSMC)模型和大鼠失血性休克模型,用荧光法检测VSMC收缩反应,用Western blot检测血管...     

TNF-α通过激活蛋白磷酸酶4调节HepG2细胞中JNK磷酸化

目的 探讨蛋白磷酸酶4(protein phosphatase 4,PP4)在肿瘤坏死因子(tumor necrosis factorα,TNF-α)诱导JNK磷酸化中的作用.方法 TNF-α处理人肝癌细胞HepG2,免疫印迹检测JNK磷酸化水平和PP4表达水平,免疫沉淀结合磷酸酶活性测定法分析PP4活性变化.构建PP...     

c-Jun氨基末端激酶在脑缺血再灌注损伤中的作用

在生物体内,丝裂原活化蛋白激酶(mitogen-activated protein kinase,MAPK)是信号从细胞表面转导至细胞核内部的重要传递者,是一类丝/苏氨酸残基的蛋白激酶。目前在真核生物细胞中,已明确了4条MAPK信号转导通路,即细胞外信号调节蛋白激酶(extracellular signal-regulated protein kinases,ERK)通路、c-Jun氨基末端激酶(c-Jun N-terminal kinase,JNK)通路、p38通路及ERK5通路。JNK信号通路作为MAPK信号通路中重要的通路之一,参与了多种生理、病理过程,目前诸多研究表明其在脑缺血/再灌注损伤过程中尤其是程序性细胞死亡过程中起着重要的调控作用,本文就近年来对JNK通路的研究及JNK在脑缺血再灌注诱导的细胞凋亡中的作用及机制作一综述。     

尿酸诱导树突状细胞成熟的信号转导机制研究

目的: 观察树突状细胞(DCs)成熟过程中MAPKs和NF-κB信号分子表达情况,探讨尿酸刺激DCs成熟的分子机制。方法: 用尿酸体外刺激大鼠未成熟 DCs,在不同时点(0~45 min),免疫印迹方法检测p- p38、p-ERK1/2、p-JNK和NF-κB p65表达情况;以MAPKs和NF-κB信号分子抑制剂分别联合尿酸刺激DCs 48 h后,用流式细胞术检测表面分子CD83、CD86、IA/IE的表达;ELISA法测定IL-12 p70的水平。结果: (1)尿酸刺激后15 min,DCs p- p38、p-ERK1/2、p-JNK和NF-κB p65表达量明显增加,30 min时达到最大值;使用相应信号分子抑制剂后,相关蛋白表达均不能测出。(2)经p38、JNK、NF-κB p65等信号通路抑制剂预处理后,与单独尿酸刺激相比,DCs CD83、CD86、IA/IE等表面分子表达及IL-12 p70分泌水平均出现下降(P＜0.05或P<0.01),ERK1/2抑制剂预处理者,则出现表达上升(P＜0.05)。结论: 尿酸可以调节DCs p38、ERK1/2、JNK、 NF-κB等信号分子的活化,从而促进DCs表面分子表达及IL-12 p70分泌。这可能为尿酸能诱导DCs成熟及提高免疫功能的分子机制之一。     

Signal transduction mediated by mitogen-activated protein kinases and apoptisis of tumor cells

Objective To make a review about MAPK and apoptosis of tumor cells.Methods We collected a large number of related experimental papers,and summarized key points.Results mitogen activated protein kinase(MAPK)is one of the four biggest signal transduction systems which contain four subtribes named p38,ERK5,ERK and JNK/SAPK respectively.MAPK pathways constitute numerous modular network that regulates a variety of physiological processes,such as cell growth,roliferation,differentiation,and apoptotic cell death.Specially,the function of induced apoptosis in tumor cells has gradually become main focus.Both in-vitro and ex-vivo findings demonstrated that in apoptotic tumor cells the level of phosphorylation of JNK kinase is significantly improved.That means JNK kinase is activated in these tumor cells.At the same time,contrary to JNK kinase,the activity of ERK kinase is usually weakened.So,for most apoptotic tumor cells,JNK is a positive factor,however,ERK kinases is a negative factor.As for the p38 kinase,which can be activated to outside stimulus,also has the promotion of apoptosis.Importantly,ERK kinase activity is suppressed by JNK/p38 kinase during apoptosis induction.Further study demonstrate that the regulatory mechanisms of MAPK in apoptotic tumor cells are:working on upstream of caspase;starting death receptor channel;activating pro-apoptotic Bcl-2 protein family;changing mitochondrial permeability;participating in Fas/Fasl-mediated apoptosis;enhancing the expression of TNF-a and so on.Conclusions The relationship between MAPK and apoptosis of tumor cells is intimate.It is expected to be a new target for tumor in clinical treatment.     

黄连解毒汤和黄连单煎剂对胰岛素抵抗大鼠氧化应激和内质网应激的影响

目的：观察黄连解毒汤、黄连单煎剂对胰岛素抵抗大鼠氧化应激和内质网应激的影响。方法：采用高脂高热卡饮食饲养8周制备胰岛素抵抗大鼠模型，成模后随机分为黄连解毒汤纽（HJD组）、黄连单煎剂组（HD组）、Alpha-硫辛酸组（ALA组）和模型组（MOD组），各组以相应的药物干预4周。另设正常组（NOR组），予普通饲料喂养，不予药物干预。比较各组大鼠空腹血糖（FBG）、空腹胰岛素水平（Fins）和胰岛素敏感性（ISI）以观察药物对大鼠糖代谢的影响，血清及肝脏中丙二醛（MDA）、超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH—Px）活性以观察药物对大鼠氧化和抗氧化的影响。Western blot方法测定肝组织中的内质网应激标志物c—Jun氨基端激酶（c-jun NH2-terminal kinase，JNK）和Phospho—c-Jun NH2-terminal kinase（Ser73）（p-c—Jun）的蛋白含量变化，RT-PCR方法检测肝组织内质网应激标志物葡萄糖调节蛋白GRP78（glucose regulated protein78，GRP78）mRNA表达水平，以观察黄连解毒汤，黄连单煎剂对胰岛素抵抗大鼠内质网应激的影响。结果：与NOR组比较，MOD组大鼠FBG升高，Fins明显升高，ISI明显降低（P〈0．01），血清及肝脏中MDA含量明显升高（P〈0．05），SC）D、GSH—PX活性明显降低（P〈0．05，P〈0．01）；与MOD组相比，HJD组，HD组大鼠FBG下降，Fins明显降低，ISI明显升高（P〈0．05，P〈0．01），SOD、GSH—Px的活性显著升高（P〈0．01，P〈0．05），MDA含量有一定程度下降但差异无显著性。比较各纽大鼠肝组织JNK蛋白表达水平，各组间差异无显著性；应激标志物pc-Jun／JNK的水平，MOD组较NOR组明显升高（P〈0．01），HJD、HD组较MOD组均明显下降（P均d〈0．01）。比较各组肝组织中内质网应激标志物GRP78／Bip mRNA水平，MOD组较NOR组显著升高（P〈0．05），HJD、HD组及ALA组较MOD纽均明显下降。结论：黄连解毒汤，黄连单煎剂能提高胰岛素抵抗大鼠的胰岛素敏感性，提高其抗氧化能力，改善其内质网应激状态，其作用机制可能与其抑制JNK通路有关。     

氯沙坦对血管紧张素Ⅱ诱导心肌肥厚中氨基末端激酶磷酸化的影响

目的探讨磷酸化C-jun N末端激酶（JNKs）在血管紧张素Ⅱ（AngⅡ）诱导的心肌细胞肥大中的表达，以及AT1-R阻滞剂对JNK磷酸化的影响。方法血管紧张素Ⅱ刺激培养新生Wistar大鼠心肌细胞，在相差显微镜下测量心肌细胞直径。^3H-亮氨酸掺入法测定心肌细胞蛋白质合成速率作为心肌细胞肥大的指标，用心肌细胞免荧光标记检测肥大心肌细胞内磷酸化JNKs蛋白含量表示JNK活性。结果AngⅡ可诱导心肌细胞肥大，表现为细胞直径显著增大，与对照组比较差异有统计学意义（P〈0．01），^1H-亮氨酸掺入量明显增加与对照组比较差异有统计学意义（P〈0.05），心肌细胞内磷酸化JNK蛋白含量增加。氯沙坦（LDs）能大部分抑制AngⅡ对JNKs的活化作用。结论JNK／SAPs途径在心肌肥厚中发挥一定作用，氯沙坦能通过拮抗AT1-R大部分抑制AngⅡ诱导肥大心肌细胞内JNKs的活化作用。     

Aluminum-induced apoptosis in cultured cortical neurons and its effect on SAPK/JNK signal transduction pathway

Aluminum exposure and apoptotic cell death has been implicated in several neurodegenerative diseases. The mechanisms by which aluminum interacts with the nervous system are only partly understood. In this study, we used cultured cortical neurons to investigate the ability of aluminum to induce the apoptosis of neurons and to explore the role of SAPK/JNK (stress-activated protein kinase or c-jun N-terminal kinase) signal transduction pathway on the apoptosis induced by aluminum. We found that aluminum-induced degeneration of cortical neurons involved the DNA fragmentation characteristic of apoptosis, and staining of aluminum-treated neurons with the DNA-binding fluorochrome Hoechst 33258 revealed the typical apoptotic condensation and fragmentation of chromatin. The rate of apoptosis increased significantly (from 4.9 to 13.1, 21.4, and 59.8%, P<0.01), which was measured by TdT-mediated dUTP nick end labeling. Western blot analysis showed that SAPK/JNK activities of cortical neurons varies when the exposure time of AlCl(3) were different. The phosphorylation levels were 4.2, 3.3, 1.9 and 1.1 times greater compared to control cultures for 6, 12, 24, and 48 h, respectively (P<0.01). Furthermore, a JNK pathway inhibitor, CEP-11004 (KT8138) inhibited the activation of SAPK/JNK to protect cortical neurons from apoptosis induced by aluminum chloride. Our study demonstrates that aluminum can induce the apoptosis of cortical neurons and SAPK/JNK signal transduction pathway may play an important role in the apoptosis.     

Variant PC12 cell line that spontaneously differentiates and extends neuritic processes

The rat pheochromocytoma PC12 cells differentiate into neuronal-like cells in response to treatment with neurotrophins. The cells have been extensively used for investigating neuronal differentiation and axonal growth. Here we report the isolation of a variant PC12 cell line, named PC12-N1, which spontaneously differentiates and extends neuritic processes. The PC12-N1 cells expressed many neuronal specific proteins, including the synaptosomal associated protein of 25 kDa (SNAP-25), synaptotagmin, and synaptobrevin (also known as VAMP). The cells also expressed neurofilament protein of 68 kDa, a marker for differentiated neurons. In addition to the spontaneous neurite outgrowth, the PC12-N1 cells showed a marked increase in neurite outgrowth upon treatment with nerve growth factor (NGF), basic fibroblast growth factor (bFGF), and cyclic AMP (cAMP). The activation of mitogen-activated protein (MAP) kinases was examined by immunoblot analysis using phospho-specific antibodies. No overactivation was observed with ERK1/2 or p38. However, the c-Jun N-terminal kinase JNK/SAPK was activated approximately 10-fold over the parental PC12 cells. These results suggest that activation of JNK/SAPK may be involved in the spontaneous neurite extension in the PC12-N1 cells. Moreover, the PC12-N1 cells may be used as a model for investigating molecular signaling mechanisms underlying neuronal differentiation and axonal outgrowth.