PKC在细胞凋亡中的作用

引起细胞凋亡的原因较多 ,目前发现蛋白激酶 C(proteinkinase C,PKC)在凋亡发生过程中起着信号传导作用。作为细胞信号传导重要成分的 PKC在细胞的凋亡中起着重要作用。PKC是一个富含丝 /苏氨基酸的激酶 ,由 77～ 2 3Kd的多肽单链构成〔1〕,除在凋亡方面发挥作用外还参与调节神经兴奋性、突触塑形、细胞增生和分化、基因表达及细胞坏死。1　PKC分类与结构根据 PKC结构及特征 ,把它们分成三大类〔1～ 3〕。经典 PKC(CPKC)包括 α、β1 、β2 和 γ四种亚型。新型 PKC(n PKC)包括 δ、ε、η、θ、ξ五种亚型。不典型 PKC(a PK…     

氧化砷诱导胃癌细胞凋亡的信号传导途径研究

目的 检测氧化砷(As2O3)诱导胃癌细胞株(SGC-7901和MKN-45)凋亡过程中cAMP、蛋白激酶C(PKC)和酪氨酸蛋白激酶(PTK)活性变化，以探讨其诱导胃癌细胞凋亡过程中可能存在的信号传导途径。方法 应用钙离子拮抗剂、PKC和PTK抑制剂研究其对AS2O3诱导胃癌细胞凋亡过程的影响，以TUNEL法检测细胞凋亡率。以放射免疫法测定As2O3作用前后细胞内cAMP水平的变化。抽提PKC和PTK蛋白，以Lowry法测定As2O3作用前后各自蛋白表达水平的变化。结果 钙离子拮抗剂对As2O3诱导胃癌细胞凋亡过程没有影响，PKC和PTK抑制剂不仅本身能诱导胃癌细胞凋亡，且对As2O3诱导胃癌细胞凋亡具有协同作用。在As2O3诱导胃癌细胞凋亡过程中存在cAMP浓度增高和PKC、PTK活性显著降低，提示cAMP、PKC和PTK可能参与As2O3诱导胃癌细胞凋亡的作用。结论 PKC和PTK抑制剂可以通过影响信号传导系统诱导胃癌细胞凋亡，并能促进As2O3诱导胃癌细胞凋亡。     

SHH信号通路在血管平滑肌细胞增殖和凋亡中的作用

目的 探讨Sonic Hedgehog(SHH)信号通路在血管平滑肌细胞增殖和凋亡中的作用.方法 在培养液中加入或不加SHH信号通路特异抑制剂Cyclopamine体外培养人血管平滑肌细胞,然后用四唑蓝(MTT)比色试验检测细胞的增殖情况,采用流式细胞术检测细胞周期,分别计算增殖指数(PI)和凋亡指数(AI).结果MTT结果显示,Cyclopamine对血管平滑肌的抑制具有时间及浓度依赖性;流式细胞术检测结果显示,Cyclopamine使血管平滑肌增殖指数降低,凋亡指数升高.结论 SHH信号通路在血管平滑肌细胞增殖和凋亡中发挥重要作用.     

PI3K/Akt信号转导通路与脑缺血后细胞凋亡

细胞凋亡为脑缺血时细胞死亡的重要形式之一.磷脂酰肌醇-3激酶(phosphoinositide-3 kinase,PI3K)/丝氨酸-苏氨酸蛋白激酶(serine/threonine kinase,Akt)为重要的细胞存活信号通路,c-Jun氨基端激酶(c-jun N-terminal kinase,JNK)为重要的促进细胞凋亡信号通路.这两大通路转导信号的动态平衡维持着生理状态下的细胞生存与凋亡.脑缺血刺激打破了这一生理平衡,导致大量神经细胞凋亡.多种确切的神经保护因素都与增强细胞存活信号的放大或抑制凋亡信号的放大有关,从而维持这2个通路信号的平衡.     

Wnt信号通路介导CIP2A沉默诱导肺癌细胞凋亡

目的探讨Wnt信号通路在沉默蛋白磷酸酶2A的癌性抑制因子(CIP2A)对肺癌细胞凋亡影响中的作用。方法以H1299细胞为探讨对象,用CIP2A shRNA慢病毒感染后,Realtime PCR和Western印迹检测沉默效果。以Western印迹检测沉默CIP2A后的肺癌细胞中β-catenin、c-myc蛋白表达水平。用Wnt信号通路激活剂处理沉默CIP2A后的肺癌细胞,噻唑蓝(MTT)法测定细胞增殖,流式细胞术检测细胞凋亡,Western印迹检测细胞中活化的含半胱氨酸的天冬氨酸蛋白水解酶(Cleaved Caspase)-3、Cleaved Caspase-9、β-catenin、c-myc蛋白水平。结论 CIP2A shRNA慢病毒感染显著降低肺癌细胞中CIP2A表达水平。沉默CIP2A后的肺癌细胞增殖活性显著降低,细胞凋亡率显著升高,细胞中Cleaved Caspase-3、Cleaved Caspase-9蛋白水平显著升高,β-catenin、c-myc蛋白水平显著降低(P0.05)。Wnt信号通路激活剂可以逆转沉默CIP2A对肺癌细胞增殖抑制、凋亡促进作用,降低细胞中Cleaved Caspase-3、Cleaved Caspase-9蛋白水平,升高细胞中β-catenin、c-myc蛋白水平。结论 Wnt信号通路参与介导沉默CIP2A对肺癌细胞凋亡诱导作用。     

姜黄素调控食管癌Eca-109细胞分化、增殖、凋亡的机制

目的探讨姜黄素对食管癌Eca-109细胞的分化、增殖、凋亡及分泌信号蛋白(Wnt)信号通路的影响及机制。方法 MTT法检测8、16、32、64μmol/L的姜黄素作用于食管癌Eca-109细胞24、48、72 h后细胞存活情况,计算细胞凋亡率,原位末端标记法(TUNEL)检测48 h后细胞凋亡情况,RT-PCR检测48 h后细胞中β连环蛋白(β-catenin)、GSK-3β、c-myc的mRNA的表达情况,Western印迹检测48 h后细胞中β-catenin、GSK-3β、c-myc蛋白的表达情况。结果姜黄素对食管癌Eca-109细胞的抑制作用随着作用时间和作用浓度的增加而增加,姜黄素作用24 h IC50为28.1μmol/L,48 h为23.2μmol/L,72 h为15.6μmol/L。TUNEL检测细胞凋亡率随着药物作用浓度的增加而增加。β-catenin、c-myc的转录水平随着药物浓度的增加而减弱。GSK-3β的转录水平随着药物浓度的增加而加强。β-catenin、c-myc蛋白表达量随着药物浓度的增加而减弱。GSK-3β蛋白表达水平随着药物浓度的增加而加强。结论姜黄素可以抑制食管癌Eca-109细胞增殖,促进细胞凋亡。姜黄素可以上调Wnt信号通路中GSK-3β酶的表达、促进β-catenin蛋白降解,从而抑制c-myc基因的转录,抑制癌细胞生长增殖。     

雌激素抑制内质网应激引起的血管内皮细胞凋亡及机制

目的通过建立人脐静脉内皮细胞(HUVEC)内质网应激(ERS)的细胞模型,研究雌激素抑制内质网应激引起的凋亡的信号传导机制,以探讨雌激素对心血管的保护机制。方法分别用10μmol/L的衣霉素(TM)或2 mmol/L的二硫苏糖醇(DTT)诱导HUVEC,建立内质网应激细胞模型,提前给予10-8mol/L的17-β雌二醇(E2)预处理1 h,用Western blot检测葡萄糖调节蛋白78(GRP78)判断模型是否建立成功,并探索E2对内质网应激的作用。检测内质网应激的三条主要信号通路蛋白的变化,上调最显著的为内质网应激最主要的信号通路。Western blot检测内质网应激凋亡蛋白C/EBP-同源蛋白(CHOP),Hochest染色检测细胞凋亡率,探索E2对内质网应激凋亡的作用。添加E2受体拮抗剂ICI182780(ERα、ERβ拮抗剂及GPER激动剂)和G15(GPER拮抗剂)后检测内质网应激最主要通路蛋白表达量的变化,探索雌激素受体在其抑制内质网应激中的作用。添加E2受体后信号通路阻断剂,检测雌激素抑制内质网应激的过程中活化其受体后激活的最主要受体后信号通路。结果 TM/DTT组GRP78的表达量显著上调,内质网应激三条信号通路中蛋白激酶R样内质网激酶(PERK)信号通路上调最明显,而TM/DTT+E2组上调显著回复。TM/DTT组CHOP的表达量显著上调且细胞凋亡率显著增加,而TM/DTT+E2组上调明显回复,凋亡细胞减少。E2有显著抑制p-PERK/PERK上调的作用,而E2的保护作用可分别被ICI182780和G15阻断,同时添加ICI182780和G15时阻断作用最显著。分别添加信号通路阻断剂后,E2抑制pPERK/PERK上调的作用均减弱,其中以磷脂酰肌醇-3羟基激酶(PI3K)通路阻断剂的作用最显著。结论 E2可抑制TM/DTT诱导的HUVEC内质网应激。p-PERK/PERK通路可能为TM/DTT诱导的HUVEC内质网应激最主要的信号通路。E2可抑制过度内质网应激引起的细胞凋亡。E2受体在E2抑制内质网应激凋亡的作用中起重要作用。E2受体激活包括PI3K-蛋白激酶B(PKB/Akt)、细胞外信号调节激酶1/2(ERK1/2)、c-Jun氨基末端激酶(JNK)和p38-丝裂原活化蛋白激酶(p38-MAPK)在内的信号通路快速起到抑制内质网应激的作用,其中PI3K-Akt通路可能为最主要的通路。雌激素通过抑制PERK信号通路引起的内质网应激凋亡,保护血管内皮细胞,其抑制内质网应激的机制主要为活化的雌激素受体激活PI3K/Akt通路。     

P38MAPK信号通路与肝纤维化

丝裂原活化蛋白激酶(mitogen activated protein kinase,MAPK)是真核细胞介导细胞外信号到细胞内反应的重要信号传导系统之一,P38MAPK是MAPK家族的重要成员,他在炎症、细胞应激、凋亡、细胞周期和生长等多种生理和病理过程中起重要作用.现从其组织结构、分布亚型、激活途径和功能等方面,对P38MAPK信号通路在肝纤维化(hepatic fibrosis,HF)过程中所起的重要作用作一综述,旨在为相关研究提供参考资料.     

白藜芦醇通过SDF-1/CXCR4信号通路诱导大肠癌细胞株SW480凋亡

[目的]探讨白藜芦醇(Res)对大肠癌细胞株SW480增殖、凋亡的影响,并研究Res对SDF-1/CXCR4信号通路的作用。[方法]以20、40、80μmol/L Res处理SW480细胞后,采用CCK8方法检测细胞增殖抑制率,流式细胞仪检测细胞凋亡率,Western Blot方法分析细胞中凋亡相关蛋白Cleaved caspase-3、Bax、Bcl-2及SDF-1/CXCR4信号通路相关蛋白的表达水平。[结果]Res处理SW480细胞后,细胞增殖抑制率明显升高,且呈时间和剂量依赖性(P0.05);Res处理后SW480细胞凋亡率也显著升高(P0.05);药物处理组中促凋亡蛋白Cleaved caspase-3、Bax表达显著升高,而抗凋亡蛋白Bcl-2及SDF-1、CXCR4蛋白表达水平显著降低,表现出剂量依赖性(P0.05)。[结论]Res抑制大肠癌细胞株SW480增殖、诱导其凋亡,其作用机制可能与降低SDF-1/CXCR4信号通路活化相关。     

辣椒素通过调节PLC-γ1信号通路对胆管癌细胞功能的影响

目的探讨辣椒素(CAP)对人胆管癌(CCA)细胞系RBE增殖及凋亡的影响。方法体外培养的RBE细胞采用0、50、100、150、200μmol/L的CAP及200μmol/L的CAP处理0、24、48、72 h,用MTT方法和流式细胞仪检测RBE细胞增殖和凋亡能力的变化,采用Western印迹方法检测RBE细胞中磷脂酶C(PLC)-γ1信号通路的磷酸化活化情况。采用PLC-γ1信号通路抑制剂U71322阻断RBE细胞中PLC-γ1信号通路后,再以CAP处理RBE细胞,MTT方法和流式细胞仪检测RBE细胞增殖和凋亡能力的变化情况。结果与0μmol/L CAP处理组相比,50、100、150、200μmol/L的CAP可显著抑制RBE细胞的增殖能力(P<0.01),并增加RBE细胞的凋亡水平(P<0.01),且这种作用具有剂量依赖性。Western印迹结果显示,CAP显著活化RBE细胞中的PLC-γ1信号通路,且随着CAP处理浓度的升高,PLC-γ1信号通路活化水平逐渐升高。U71322阻断RBE细胞中的PLC-γ1信号通路后,CAP抑制RBE细胞的增殖能力显著降低(P<0.01)。结论通过活化PLC-γ1信号通路,CAP可抑制RBE细胞的增殖能力,并促进RBE细胞凋亡。     

STAT3在炎症性肠病中的作用研究进展

肠黏膜的免疫反应失控是炎症性肠病的特征性表现。机体的免疫和炎症系统被多种细胞因子调控,这些细胞因子如白细胞介素(IL)、干扰素等通过Janus激酶/信号转导和转录激活因子(JAK/STAT)途径发挥其生物功能。在炎症性肠病患者及小鼠结肠炎模型中均发现在STAT家族中以STAT3磷酸化程度最高,这提示STAT3的活化在炎症性肠病的发病中可能起着重要作用。此文就STAT3的功能、调节机制及其在炎症性肠病中可能发挥的作用的最新研究进行综述。     

Involvement of phosphatidylinositol 3 kinase in the progesterone-induced oocyte maturation in Rana dybowskii

Previously, we observed that 70-kDa ribosomal protein S6 kinase (p70(s6k)) plays an essential role during the early phase of oocyte maturation in Rana dybowskii. To investigate further the early signal transduction components involved in this process, the possible role of phosphatidylinositol-3 kinase (PI3 kinase) during oocyte maturation was examined. Progesterone-induced oocyte maturation was significantly inhibited by wortmannin and LY294002, specific inhibitors of PI3 kinase. In contrast, protein kinase C activator 12-0-tetradecanoylphorbol-13-acetate-induced oocyte maturation was not inhibited by wortmannin. Protein synthesis was also significantly suppressed by wortmannin treatment during oocyte maturation. Moreover, PI3 kinase inhibitor suppressed progesterone-induced phosphorylation of S6 kinase in a dose-dependent manner. Likewise, PI3 kinase inhibitors significantly inhibited the phosphorylation of mitogen-activated protein (MAP) kinase which was increased during oocyte maturation. Finally, progesterone-induced H1 kinase activity was also inhibited by PI3 kinase inhibitors in a dose-dependent manner. Taken together, these results suggest that PI3 kinase is an initial component of the signal transduction pathway which precedes p70(s6k), MAP kinase, and MPF production during progesterone-induced maturation of amphibian oocyte.     

Flt3-dependent transformation by inactivating c-Cbl mutations in AML

In acute myeloid leukemia (AML), mutational activation of the receptor tyrosine kinase (RTK) Flt3 is frequently involved in leukemic transformation. However, little is known about a possible role of highly expressed wild-type Flt3 in AML. The proto-oncogene c-Cbl is an important regulator of RTK signaling, acting through its ubiquitin ligase activity and as a platform for several signaling adaptor molecules. Here, we analyzed the role of c-Cbl in Flt3 signal transduction and myeloid transformation. C-Cbl physically interacted with Flt3 and was tyrosine phosphorylated in the presence of Flt3-ligand (FL). Overexpression of a dominant-negative form of c-Cbl (Cbl-70Z) inhibited FL-induced Flt3 ubiquitylation and internalization, indicating involvement of c-Cbl in Flt3 signaling. DNA sequencing of AML bone marrow revealed a case with a c-Cbl point mutation (Cbl-R420Q). Cbl-R420Q inhibited Flt3 internalization and ubiquitylation. Coexpression of Cbl-R420Q or Cbl-70Z with Flt3 induced cytokine-independent growth and survival of 32Dcl3 cells in the absence of FL. Also, the mutant Cbl proteins altered the amplitude and duration of Flt3-dependent signaling events. Our results indicate an important role of Cbl proteins in Flt3 signal modulation. Also, the data suggest a novel mechanism of leukemic transformation in AML by mutational inactivation of negative RTK regulators.     

FLT3 inhibition in t(4;11)+ adult acute lymphoid leukaemia

The present study was designed to investigate, in t(4;11)+ adult lymphoid leukaemia (ALL) blast cells, the pathogenetic role of the FLT3 protein, its level of mRNA and protein expression, the degree of constitutive phosphorylation, the possible presence of mutations of the sequence, the capacity of signal transduction and the potential therapeutic role of specific inhibitors. We evaluated nine adult ALL patients carrying this translocation. The increased FLT3 mRNA levels, determined by oligonucleotide microarray analysis, was in agreement with the increased protein expression evaluated by Western blot. The protein was constitutively phosphorylated in all cases analysed. Polymerase chain reaction detected no internal tandem duplication or point mutations. The signal transduction apparatus, after stimulation with the specific ligand, was preserved. We then investigated the effect of specific FLT3 inhibition on signal transduction and survival. The PKC412 inhibitor specifically inhibited ligand-induced phosphorylation; the same inhibitor reduced the survival of leukaemic cells when compared with untreated cells. These data indicate that the FLT3 protein might play a role in this subgroup of ALL with a particularly poor prognosis. Specific inhibition of the kinase receptor must be hypothesised as an innovative therapeutic tool for t(4;11)+ ALL patients.     

Granulocyte-macrophage colony-stimulating factor and interleukin-3 induce rapid phosphorylation and activation of the proto-oncogene Raf-1 in a human factor-dependent myeloid cell line.

The product of the c-raf-1 proto-oncogene, Raf-1, is a 74,000-dalton cytoplasmic serine/threonine protein kinase that has been implicated as an intermediate in signal transduction mechanisms. In the human factor-dependent myeloid cell line MO7, both granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin-3 (IL-3) were found to induce rapid, dose-dependent phosphorylation of Raf-1, which resulted in altered Raf-1 mobility in sodium dodecyl sulfate-polyacrylamide gels. The increase in phosphorylation was due primarily to an increase in phosphoserine, with only a minor component (less than 2%) of phosphotyrosine. PMA (12-phorbol 13-myristic acid) also induced Raf-1 phosphorylation in MO7 cells, but the resulting alteration in electrophoretic mobility was different than that observed after GM-CSF or IL-3. GM-CSF and IL-3 rapidly and transiently increased Raf-1 kinase activity using Histone H1 as a substrate in an immune complex kinase assay in vitro. These results suggest that phosphorylation of Raf-1 could play a role in some aspect of GM-CSF and IL-3 signal transduction.     

PI3K与支气管哮喘发作期T细胞增殖周期蛋白关系的研究进展

T细胞是支气管哮喘(简称哮喘)发病机制中的核心细胞.T细胞增殖周期异常在哮喘中发挥着重要作用.PI3K信号转导途径是T细胞内重要的信号转导途径,与细胞周期蛋白异常密切相关,其机制的研究对于哮喘的治疗有重要的意义.     

CX3CR1 is required for monocyte homeostasis and atherogenesis by promoting cell survival

CX(3)CR1 is a chemokine receptor with a single ligand, the membrane-tethered chemokine CX(3)CL1 (fractalkine). All blood monocytes express CX(3)CR1, but its levels differ between the main 2 subsets, with human CD16(+) and murine Gr1(low) monocytes being CX(3)CR1(hi). Here, we report that absence of either CX(3)CR1 or CX(3)CL1 results in a significant reduction of Gr1(low) blood monocyte levels under both steady-state and inflammatory conditions. Introduction of a Bcl2 transgene restored the wild-type phenotype, suggesting that the CX(3)C axis provides an essential survival signal. Supporting this notion, we show that CX(3)CL1 specifically rescues cultured human monocytes from induced cell death. Human CX(3)CR1 gene polymorphisms are risk factors for atherosclerosis and mice deficient for the CX(3)C receptor or ligand are relatively protected from atherosclerosis development. However, the mechanistic role of CX(3)CR1 in atherogenesis remains unclear. Here, we show that enforced survival of monocytes and plaque-resident phagocytes, including foam cells, restored atherogenesis in CX(3)CR1-deficent mice. The fact that CX(3)CL1-CX(3)CR1 interactions confer an essential survival signal, whose absence leads to increased death of monocytes and/or foam cells, might provide a mechanistic explanation for the role of the CX(3)C chemokine family in atherogenesis.