肿瘤坏死因子-α诱导心肌肥大中CaN信号通路的作用

目的:研究钙调神经磷酸酶(CaN)信号通路在肿瘤坏死因子-α(TNF-α)诱导心肌细胞肥大中的作用。方法:Lowry法测心肌细胞蛋白含量;计算机图象分析系统测心肌细胞体积;[3H]-亮氨酸掺入法测心肌细胞蛋白合成;Till阳离子测定系统观察胞内[Ca2+]i瞬变;Western blot法测定CaN的表达。结果:①CaN特异性抑制剂CsA(0.2μmol/L)明显抑制TNF-α(100μg/L)诱导的心肌细胞蛋白含量、蛋白合成和细胞体积增大,但对正常心肌细胞生长无影响。②CaN特异性抑制剂CsA(0.2μmol/L)明显降低TNF-α诱导的心肌细胞内钙离子浓度([Ca2+]i)瞬变幅度增高。③TNF-α明显增强心肌细胞内CaN的表达。结论:TNF-α可能通过引起心肌细胞[Ca2+]i升高,促进CaN表达诱导心肌细胞肥大。     

肿瘤坏死因子α在中枢神经系统中的作用

概述了肿瘤坏死因子α（TNFα）及其受体在中枢神经系统（CNS）中的作用。TNFα在神经元和胶质细胞中的表达量与神经系统疾病的发病密切相关;TNFα与神经胶质增生、Alzheimer’s病、Parkinson病和多发性硬化症都有关系。然而;当CNS受损伤以后,TNFα能够促进神经营养因子的分泌,增强神经元的粘附和促进轴突的生长;这是它有利的一面。这种双重模式的效应与其受体亚型和激活不同的信号转导途径有关。所以,在CNS的发育中,TNFα可能是一个重要的调节因子。     

PI3K/AKT通路在动物葡萄糖代谢中的研究进展

葡萄糖代谢稳态对维持动物健康水平至关重要.磷脂酰肌醇3-激酶(phosphoinositide 3-kinase,PI3K)是受体酪氨酸激酶(receptor tyrosine kinase,RTK)和G蛋白偶联受体(G protein-coupled receptor,GPCR)共同调控的下游效应因子.它能够磷酸化磷...     

PI3K/AKT途径在大肠埃希菌诱导U937细胞凋亡中的作用

目的探讨PI3K/AKT信号转导通路在大肠埃希菌（Escherichia coli,E.coli）诱导的人巨噬细胞系U937细胞凋亡中的作用。方法利用Western blot分析检测E.coli感染不同时间后磷酸化及非磷酸化AKT的表达;预先用不同浓度的LY294002（PI3K途径抑制剂）处理U937细胞60min,观察E.coli感染30min后U937细胞的凋亡情况。结果随着感染时间的延长,磷酸化AKT的表达逐渐下降。加入PI3K的抑制剂LY294002后,U937细胞的凋亡率逐渐升高。结论PI3K/AKT信号转导通路参与了E. coli诱导的U937细胞凋亡过程。LY294002通过特异性地抑制PI3K/AKT活性增加E.coli诱导的U937细胞凋亡率。     

PGE2抑制肿瘤坏死因子诱导的成骨细胞凋亡

前列腺素E2(PGE2)通过自分泌或旁分泌方式调节成骨细胞的增殖和分化。本文以小鼠原代成骨细胞和成骨样细胞MC3T3-E1为实验材料,研究了PGE2对肿瘤坏死因子α(TNF-α)诱导的成骨细胞凋亡的调节作用。检测发现,振荡型流体剪切力(OFSS)刺激可诱导成骨细胞内环氧合酶2(COX-2)表达升高,进而促进PGE2合成,并抑制TNF-α诱导的成骨细胞凋亡。COX-2选择性活性抑制剂NS-398显著促进TNF-α诱导的成骨细胞内半胱天冬酶3(caspase-3)的激活,且呈时间依赖性。Hoechst 33258/PI染色检测发现,NS-398促使TNF-α诱导的成骨细胞膜通透性进一步增强,核染色质浓缩加剧,而PGE2可显著抑制这一效应。Caspase-3活性检测证实,NS-398显著促进TNF-α诱导的成骨细胞内caspase-3活性增强,外源性PGE2可有效对抗该效应。这些结果表明,内源性和外源性PGE2可抑制TNF-α诱导的成骨细胞凋亡发生。     

PI3K/Akt/mTOR信号通路及临床相关肿瘤抑制剂

哺乳动物雷帕霉素靶（mTOR）和蛋白激酶B（Akt/PKB）与肿瘤发生的密切关系已被广泛地认可.mTOR是一种丝/苏氨酸激酶,可以通过影响mRNA转录、代谢、自噬等方式调控细胞的生长.它既是PI3K的效应分子,也可以是PI3K的反馈调控因子.mTORC1 和mTORC2是mTOR的两种不同复合物. 对雷帕霉素敏感的mTORC1受到营养、生长因子、能量和应激4种因素的影响.生长因子通过PI3K/Akt信号通路调控mTORC1是最具特征性调节路径.而mTORC2最为人熟知的是作为Akt473磷酸化位点的上游激酶. 同样,Akt/PKB在细胞增殖分化、迁移生长过程中发挥着重要作用. 随着Thr308和Ser473两个位点激活,Akt/PKB也得以全面活化.因此,mTORC2-Akt-mTORC1的信号通路在肿瘤形成和生长中是可以存在的.目前临床肿瘤治疗中,PI3K/Akt/mTOR是重要的靶向治疗信号通路.然而,仅抑制mTORC1活性,不是所有的肿瘤都能得到预期控制.雷帕霉素虽然能抑制mTORC1,但也能反馈性地增加PI3K信号活跃度,从而影响治疗预后.近来发现的第二代抑制剂可以同时抑制mTORC1/2和PI3K活性,这种抑制剂被认为在肿瘤治疗上颇具前景.本综述着重阐述了PI3K/Akt/mTOR信号通路的传导、各因子之间的相互调控以及相关抑制剂的发展.     

中国人群中肿瘤坏死因子α-308 A/G基因多态和α2-巨球蛋白基因缺失多态与晚发性阿尔茨海默病无相关性

晚发性阿尔茨海默病 (LOAD)是老年痴呆中最常见的一种 ,它是一种病因复杂、由遗传因素和环境等其他因素共同作用引起的老年期疾病。服用非甾类抗炎类药物能延缓或防止LOAD的发病说明炎症反应可能参与LOAD病理 ,肿瘤坏死因子 (TNF)是炎症反应中主要的细胞因子 ,并且能增加 β 淀粉样肽 (Aβ)的产生说明其可能是LOAD的易感基因。α2 巨球蛋白 (A2M)是一种血清蛋白酶抑制剂 ,它是低密度脂蛋白受体相关蛋白 (LRP)主要的配体 ,并且能与Aβ结合并介导其降解和清除 ,说明它可能是另一个LOAD的易感基因。在 6 7名晚发性阿尔茨海默病人和 14 2名正常对照中比较了载脂蛋白E基因 (APOE)、TNF启动子区 (- 30 8A G)多态和A2M一 5bp核苷酸缺失 (I D)多态 (A2M 2 )与LOAD发病风险的关系。结果显示 ,APOEε4等位基因在AD病人组中显著高于对照组 (χ2=11 6 6 ,P <0 0 1) ,而TNF(- 30 8A G)多态和A2M缺失多态的基因型和等位基因在LOAD病人组和对照组中都无显著差别 (P >0 1)。按年龄和APOEε4等位基因分组同样无相关性 ,说明TNF 30 8A G位点的多态与A2M缺失不是中国人群的晚发性老年痴呆的风险因子     

镉负荷大鼠一氧化氮和肿瘤坏死因子-α释放在介导多器官机能活动障碍中的作用

选择健康SD雄性成年大鼠36只,随机分成对照组(C组)、镉负荷中剂量组(M组)、镉负荷高剂量组(H组).将分析纯CdCl2·2.5H2O用生理盐水稀释成含镉0.4 mg/ml浓度的注射溶液,高压灭菌.M组和H组大鼠每天分别按含镉0.5和1.0 mg/kg体重腹腔注射染毒,C组用同样方法注射与H组同等剂量的生理盐水,进行急性镉负荷实验,连续观察7 d.研究急性镉负荷对大鼠血液及几种组织中一氧化氮(NO)自由基、肿瘤坏死因子-α(TNF-a)变化的影响及作用.结果显示在整个实验期内,镉负荷大鼠体重与对照组比较明显下降;睾丸、心脏和肝脏组织中的镉含量极显著上升,并随镉负荷剂量和时间而增加;血浆NO水平M组虽高于对照组,但差异不显著,而H组极显著高于对照组,M和H组血浆TNF-α明显高于对照组;在整个实验期内,镉负荷大鼠睾丸、心脏和肝脏组织匀浆中NO较对照组高或明显高于对照组,睾丸和心脏组织匀浆中TNF-a也均高于或明显高于对照组,但肝脏中的TNF-a三组间没有差异.结果提示,镉负荷诱发NO、TNF-α大量释放在导致大鼠多种器官机能活动障碍发生过程中可能起重要作用.     

PEMT2过表达抑制大鼠肝癌细胞PI3K, Akt的表达(英)

为探讨磷脂酰乙醇胺-N-甲基转移酶2(PEMT2)过表达抑制大鼠肝癌细胞增殖的机制,构建了PEMT2高表达细胞克隆,并采用半定量RT-PCR、免疫细胞化学及流式细胞仪技术,研究了PEMT2过表达对PI3K/Akt信号转导途径的影响.实验结果显示,PEMT2过表达可抑制细胞PI3K和Akt的表达,并诱导细胞凋亡.这一结果提示,PI3K/Akt信号转导途径下调可能是PEMT2抑制肝癌细胞增殖的部分机制.     

PPARδ activation inhibits angiotensin II induced cardiomyocyte hypertrophy by suppressing intracellular Ca2+ signaling pathway

Peroxisome proliferator‐activated receptors δ (PPARδ) is known to be expressed ubiquitously, and the predominant PPAR subtype of cardiac cells. However, relatively less is known regarding the role of PPARδ in cardiac cells except that PPARδ ligand treatment protects cardiac hypertrophy by inhibiting NF‐κB activation. Thus, in the present study, we examined the effect of selective PPARδ ligand L‐165041 on angiotensin II (AngII) induced cardiac hypertrophy and its underlying mechanism using cardiomyocyte. According to our data, L‐165041 (10 µM) inhibited AngII‐induced [³H] leucine incorporation, induction of the fetal gene atrial natriuretic factor (ANF) and increase of cardiomyocyte size. Previous studies have implicated the activation of focal adhesion kinase (FAK) in the progress of cardiomyocyte hypertrophy. L‐165041 pretreatment significantly inhibited AngII‐induced intracellular Ca²⁺ increase and subsequent phosphorylation of FAK. Further experiment using Ca²⁺ ionophore A23187 confirmed that Ca²⁺ induced FAK phosphorylation, and this was also blocked by L‐165041 pretreatment. In addition, overexpression of PPARδ using adenovirus significantly inhibited AngII‐induced intracellular Ca²⁺ increase and FAK expression, while PPARδ siRNA treatment abolished the effect of L‐165041. These data indicate that PPARδ ligand L‐165041 inhibits AngII induced cardiac hypertrophy by suppressing intracellular Ca²⁺/FAK/ERK signaling pathway in a PPARδ dependent mechanism. J. Cell. Biochem. 106: 823–834, 2009. © 2009 Wiley‐Liss, Inc.     

钙调神经磷酸酶信号通路参与钙激动剂介导的心肌细胞肥大

目的在于探讨不同来源的细胞内游离钙(［Ca2+］i）对钙调神经磷酸酶（calcineurin,CaN）依赖信号通路和心肌细胞肥大的影响。方法以原代培养的乳鼠心肌细胞为模型,血管紧张素Ⅱ（AngⅡ）、雷尼丁（RY）和三磷酸肌醇（IP3）（浓度均为10-7mol／L）激活心肌细胞［Ca2+］i,应用钙荧光指剂Fura-2／AM动态观测心肌细胞［Ca2+］i浓度,同时检测心肌细胞CaN活性及蛋白表达。用氚-亮氨酸（3H-Leu）掺入量测定心肌细胞蛋白质合成速率。结果发现AngⅡ、RY和IP3明显增加心肌细胞［Ca2+］i浓度、CaN活性及蛋白表达并提高3H-Leu的掺入量,与对照组心肌细胞相比差异显著（P＜0．01）。结论激活心肌细胞［Ca2+］i可明显提高心肌细胞蛋白合成速率,心肌细胞CaN活性及蛋白表达似与细胞［Ca2+］i变化有明显关系而与其来源无关,表明CaN信号通路在心肌细胞生长中发挥重要作用。     

PI3-kinase activation by GM-CSF in endothelium is upstream of Jak/Stat pathway: role of alphaGMR

GM-CSF has been identified as a growth factor for endothelial cells. In this study, we investigated the role of PI3-kinase pathway in mediating GM-CSF induced angiogenesis. GM-CSF induced tube formation in human umbilical vein endothelial cells, as examined using Matrigel assay, was inhibited by specific inhibitors of PI3-kinase, wortmannin, and LY294002. The regulatory subunit of PI3-kinase (p85) interacted with alphaGMR via its C-SH2 domain in a GM-CSF-dependent fashion with concomitant phosphorylation of p85 and activation of PI3-kinase pathway. p85 binding site on the alphaGMR was essential to induce GM-CSF receptor-dependent Stat activation. Furthermore, inhibition of PI3-kinase activity also abrogated GM-CSF induced Stat activation. These studies underscore the significance of the GM-CSF mediated PI3-kinase activation and its role in angiogenesis.     

The role of microRNAs involved in PI3-kinase signaling pathway in colorectal cancer

In recent decades, cancer has been one of the most important concerns of the human community, which affects human life from many different ways, such as breast, lung, colorectal, prostate, and other cancers. Colorectal cancer is one of the most commonly diagnosed cancers in the world that has recently been introduced as the third leading cause of cancer deaths in the world. microRNAs have a very crucial role in tumorgenesis and prevention of cancer, which plays a significant role with influencing various factors through different signaling pathways. Phosphoinositide 3 (PI3)-kinase/AKT is one of the most important signaling pathways involved in the control and growth of tumor in colorectal cancer, through important proteins of this pathway, such as PTEN and AKT, that they can perform specific influence on this process. Our effort in this study is to collect microRNAs that act as tumor suppressors and oncomirs in this cancer through PI3-kinase/AKT signaling pathway.     

A static pressure sensitive receptor APJ promote H9c2 cardiomyocyte hypertrophy via PI3K-autophagy pathway

This study is designed to investigate whether APJ receptor acts as a sensor in static pressure-induced cardiomyocyte hypertrophy and to investigate the mechanism of PI3K- autophagy pathway. The left ventricular hypertrophy rat model was established by coarctation of abdominal aorta. H9c2 rat cardiomyocytes were cultured in the presence of static pressure which was given by a custom-made pressure in- cubator. The results revealed that the expression of apelin/ APJ system, PI3K, Akt and their phosphorylation were sig- nificantly increased in the operation group. Static pressure up-regulated the APJ expression, PI3K phosphorylation, Akt phosphorylation, LC3-Ⅱ/Ⅰ and beclin-1 expression in cardio- myocytes. APJ shRNA pGPU6/Neo-rat-399, PI3K inhibitor LY294002, Akt inhibitor 1701-1 blocked the up-regulation of APJ, PI3K phosphorylation, Akt phosphorylation, LC3-H/I and beclin-1 expression, respectively. Moreover, static pres- sure increased the diameter, volume, protein content of cells, and these could be reversed when the cells were treated with pGPU6/Neo-rat-399, LY294002, and autop- hagy inhibitor 3-methyladenine, respectively. These results suggested that static pressure up-regulates APJ expression to promote cardiomyocyte hypertrophy by a PI3K-autop- hagy pathway.     

PI3K/Akt信号通路的调控与肿瘤血管生成

肿瘤对人类的生存危害极大,恶性肿瘤的治疗一直是世界性的难题。肿瘤血管生成是肿瘤赖以生长、转移的基础,受多种因子的调节。目前发现有多条信号网络参与调控肿瘤血管生成,PI3K/Akt是其中比较重要的一条信号传导途径,该通路与肿瘤的发生发展密切相关。本文介绍了PI3K/Akt信号通路的结构组成与活性调控,并重点阐述PI3K/Akt信号途径与肿瘤血管生成的关系。     

Importance of PI3-kinase pathway in response/resistance to aromatase inhibitors

Endocrine therapy has been the most effective treatment modality for hormone receptor positive breast cancer. However, its efficacy has been limited by either de novo or acquired resistance. Recent data indicates that activation of the phosphatidylinositol 3-kinase (PI3K) signaling is associated with the poor outcome luminal B subtype of breast cancer and accompanied by the development of endocrine therapy resistance. Importantly, inhibition of PI3K pathway signaling in endocrine resistant breast cancer cell lines reduces cell survival and improves treatment response to endocrine agents. Interestingly, mutations in PIK3CA, the alpha catalytic subunit of the class IA PI3K, which renders cells dependent on PI3K pathway signaling, is the most common genetic abnormality identified in hormone receptor positive breast cancer. The synthetic lethality observed between estrogen deprivation and PI3K pathway inhibition in estrogen receptor positive (ER+) breast cancer cell lines provides further scientific rational to target both estrogen receptor and the PI3K pathway in order to improve the outcome of ER+ breast cancer.     

Recombinant tissue factor pathway inhibitor induces apoptosis in cultured rat mesangial cells via its Kunitz-3 domain and C-terminal through inhibiting PI3-kinase/Akt pathway

Tissue factor pathway inhibitor (TFPI) is an endogenous inhibitor of tissue factor (TF) induced coagulation. In addition to its anticoagulation activity, TFPI has other functions such as antiproliferation and inducing apoptosis. In the present study, we investigated whether or not TFPI induced apoptosis in cultured rat mesangial cells (MsCs) and the possible signal pathway that involved in the apoptotic process. We demonstrated that recombinant TFPI (rTFPI) induced apoptosis in cultured MsCs via its Kunitz-3 domain and C-terminal in a dose- and time-dependent manner by Hoechst 33258 assay, flow cytometry, nucleosomal laddering of DNA, caspase 3 assay. Because the serine/threonine protein kinase Akt has attracted attention as a mediator of survival (anti-apoptotic) signal in MsCs, we investigated the expression of phosphospecific-Akt and its downstream signal phospho-IκB-α and some other signal molecules like Fas and bcl-2. The results indicated that the process of apoptosis triggered by rTFPI is, at least in part, actively conducted by rat MsCs possibly through PI3-Kinase-Akt signal pathway not by binding to tissue factor. Our findings suggest that rTFPI has the potential usefulness in inducing apoptosis of MsCs under inflammatory conditions.