乙肝病毒X蛋白结合蛋白(HBXIP)增强肝癌细胞NF-κB转录活性的实验研究

前期研究结果表明,乙型肝炎病毒X蛋白结合蛋白(hepatitis B virus X-interacting protein,HBXIP)具有促进细胞增殖的作用.为了进一步阐明其分子机制,观察了HBXIP对核因子κB(NF-κB)转录活性的影响.实验中通过基因共转染将NF-κB报告基因质粒pNF-κB-Luc和HBXIP真核表达载体pcDNA3-hbxip导入人肝癌H7402细胞系中,进行荧光素酶活性分析.结果显示:H7402细胞过表达HBXIP后NF-κB的转录活性明显增强;此外,基因转染后经免疫印迹检测显示,与NF-κB二聚体结合的抑制亚基IκBα的磷酸化水平明显增加;同时,提取H7402细胞的核蛋白,然后应用免疫印迹检测细胞核中p65/NF-κB的水平.结果显示,H7402细胞中HBXIP过表达后细胞核中p65/NF-κB的水平明显增加.当应用RNA干扰技术抑制了细胞内源性的HBXIP基因表达后,则出现与上述结果相反的效果.上述结果提示,HBXIP可增加核内p65/NF-κB蛋白水平,进而发挥NF-κB促转录调控的作用.因此,HBXIP可通过调控NF-κB信号途径而促进细胞增殖.     

LRP16影响电离辐射诱导的NF-κB活性

目的:研究LRP16在电离辐射激活核转录因子NF-κB信号转导通路中的作用。方法:在HeLa细胞中,分别运用双萤光素酶分析和Western印迹检测LRP16对κB-Luc报告基因及NF-κB下游靶基因表达的影响。结果:双萤光素酶实验证实LRP16过表达促进电离辐射诱导的κB-Luc活性,而抑制LRP16则降低电离辐射诱导的κB-Luc活性;Western印迹结果显示,LRP16过表达促进电离辐射诱导NF-κB的下游抗凋亡基因XIAP的表达,与之相对应的是,抑制LRP16降低电离辐射诱导NF-κB下游抗凋亡基因XIAP的表达。结论:LRP16可以调节电离辐射诱导NF-κB的转录活性,并且调控NF-κB下游抗凋亡基因XIAP的表达,为进一步阐明电离辐射激活NF-κB转录活性的分子机制奠定了基础。     

EWS蛋白质抑制核因子κB的转录活性

目的:研究EWS蛋白质是否参与核因子κB(NF-κB)信号通路,以及EWS蛋白质对NF-κB转录活性的影响。方法:在真核细胞中表达Flag-EWS,利用Western印迹检测其表达;通过双萤光素酶光报告系统,研究EWS蛋白质对NF-κB转录活性的影响及其发挥作用的分子水平。结果:Western印迹检测到相对分子质量为95×103的Flag-EWS能够在真核细胞中正确表达,过表达EWS蛋白质能够抑制TNFα、IL-1β及poly(I:C)激活的NF-κB转录活性;EWS蛋白质能够抑制由过表达HA-TRAF2或HA-p65激活的NF-κB转录活性,其抑制NF-κB转录活性发生在p65转录因子水平。结论:过表达EWS能够抑制多种刺激激活的NF-κB转录活性,这种抑制作用发生在p65转录因子水平。     

牙龈卟啉单胞菌感染对hPDL细胞中成骨标志基因表达及炎症因子分泌的影响

目的观察牙龈卟啉单胞菌(P.gingivalis)感染对人牙周膜(hPDL)细胞中成骨标志基因表达及炎症因子分泌的影响。方法原代hPDL细胞,分为P.gingivalis感染的P.gingivalis组、常规处理的对照组,成骨诱导后茜素红染色检测矿化结节,PCR法检测成骨标志基因Runt相关转录因子2(RUNX2)、骨钙素(OCN)、骨保护素(OPG)、骨碱性磷酸酶(BALP)的mRNA表达量,ELISA法检测炎症因子肿瘤坏死因子-α(TNF-α)、白细胞介素(IL)-1β、IL-6的分泌量,Western blot检测核因子-κB(NF-κB)及NF-κB抑制蛋白(I-κB)的蛋白表达量。结果与对照组比较,P.gingivalis组细胞成骨诱导后茜素红染色的矿化结节明显减少,细胞中RUNX2、OCN、OPG、BALP的mRNA表达量及I-κB的蛋白表达量均明显降低,培养基中TNF-α、IL-1β、IL-6的分泌量及细胞中NF-κB的蛋白表达量均明显增加。结论 P.gingivalis感染hPDL细胞后能够抑制成骨分化、激活炎症反应且该作用与NF-κB通路的激活有关。     

核因子

核因子κB(nuclear factor κB,NF-κB)是一种广泛存在于各种细胞、具有多种调节作用的转录因子.它在正常情况下在胞浆内与抑制蛋白(IκB)结合而呈非活性状态.当细胞受到各种刺激原如紫外辐射、细胞因子(如TNF-α、IL1)、活性氧作用时,NF-κB与IκB解离并进入细胞核内,与特定的启动子结合,从而调控各种基因的表达,如细胞因子、炎症因子、黏附分子等.NF-κB在炎症发生时复杂的细胞因子网络中起着中心调节作用.在细胞增殖、分化和凋亡及肿瘤发生中NF-κB也扮演着重要角色.以NF-κB作为药物作用的靶点,通过调节NF-κB的活性,可改善某些疾病的治疗效果.     

异丙酚对大鼠心肌缺血/再灌注损伤时NF-κB活化和细胞凋亡的影响

目的:观察异丙酚对大鼠心肌缺血/再灌注时核因子-κB(NF-κB)的活化和细胞凋亡的影响,以探讨异丙酚的心肌保护作用机制。方法:采用阻断大鼠左冠状动脉前降支30min,再灌注2h心肌缺血/再灌注损伤模型。60只SD大鼠随机分为假手术组(Sham)、缺血/再灌注组(I/R)和异丙酚3、6、12mg/(kg.h)组。光、电镜观察心肌组织的形态学变化。免疫组化染色分析心肌组织中NF-κB的核移位,Western blot检测心肌组织NF-κB和caspase-3的表达。原位末端标记(TUNEL)检测心肌细胞凋亡。结果:I/R组心肌纤维排列紊乱,心肌细胞水肿;线粒体膜肿胀,嵴排列紊乱甚至溶解消失。与I/R组相比,6,12mg/(kg·h)组异丙酚组心肌损伤明显减轻。与Sham组相比,I/R组NF-κB活化,明显从细胞浆移位于细胞核,表达量也显著增加(P0.05);心肌caspase-3表达增强(P0.01),心肌细胞凋亡指数升高(P0.05)。而异丙酚6mg/(kg·h)、12mg/(kg·h)组,NF-κB从细胞浆向细胞核的移位被明显限制,NF-κB的表达量也明显低于I/R组(P均0.05);心肌caspase-3表达减弱,心肌细胞凋亡指数减少(与I/R组相比,P0.05)。结论:异丙酚的心肌保护作用可能与其抑制NF-κB的活化,下调caspase-3的表达,从而抑制心肌细胞凋亡有关。     

过表达MicroRNA-199a促进TNFα诱导的脂肪细胞凋亡

旨为探明micro RNA-199a(mi R-199a)对脂肪细胞凋亡的影响及核转录因子κB(nuclear factorκB,NF-κB)在其中的作用。培养3T3-L1脂肪细胞,使用肿瘤坏死因子α(tumor necrosis factorα,TNFα)诱导细胞凋亡。在此基础上分别使用NF-κB阻断剂PDTC和mi R-199a mimic处理细胞,判断过表达mi R-199a对TNFα诱导的脂肪细胞凋亡的影响及NF-κB在其中的作用。使用流式细胞仪分析细胞凋亡率,试剂盒检测Caspase3/7酶活,双荧光素酶报告系统检测NF-κB活性,q RT-PCR检测mi R-199a的表达水平,Western blotting检测NF-κB相关蛋白变化。结果显示,TNFα可以诱导分化的脂肪细胞凋亡并同时激活NF-κB,激活的NF-κB在TNFα诱导的脂肪细胞凋亡中发挥负调控作用。在脂肪细胞过表达mi R-199a明显抑制NF-κB的激活进而显著促进TNFα诱导的凋亡。mi R-199a通过调控NF-κB活性参与TNFα诱导的脂肪细胞凋亡。     

MicroRNA与NF-κB调控的细胞凋亡

NF-κB是一种非常重要的核转录调控因子,激活后的NF-κB通过调节靶基因的转录表达参与细胞的各项生命活动,特别是炎症、免疫和凋亡。NF-κB在不同类型的细胞凋亡中可能发挥不同的调控作用。而microRNA这类非编码的RNA对于NF-κB的表达和功能又能够产生系统性或者特异性的调节。综述分析NF-κB对细胞凋亡的调控作用,并探讨microRNA在此过程中的作用。     

核因子κB研究进展

核因子κB(nuclear factor κB,NF-κB)是一种广泛存在于各种细胞、具有多种调节作用的转录因子。它在正常情况下在胞浆内与抑制蛋白(IκB)结合而呈非活性状态。当细胞受到各种刺激原如紫外辐射、细胞因子(如TNF-α、IL-1)、活性氧作用时,NF-κB与IκB解离并进入细胞核内,与特定的启动子结合,从而调控各种基因的表达,如细胞因子、炎症因子、黏附分子等。NF-κB在炎症发生时复杂的细胞因子网络中起着中心调节作用。在细胞增殖、分化和凋亡及肿瘤发生中NF-κB也扮演着重要角色。以NF-κB作为药物作用的靶点,通过调节NF-κB的活性,可改善某些疾病的治疗效果。     

NF-κB介导哮喘过敏原刺激后支气管上皮细胞的凋亡

目的研究核转录因子κB(NF-κB)在哮喘过敏原刺激后支气管上皮细胞中的表达及对细胞凋亡的影响。方法以300U/L尘螨抗原提取物作为过敏原刺激支气管上皮细胞系16HBE细胞,应用RT-PCR和Western blot检测尘螨抗原提取物刺激对16HBE细胞NF-κB(p65)表达水平的影响;用NF-κB(p65)sh RNA沉默16HBE细胞内NF-κB表达后,应用流式细胞术和Western blot检测NF-κB(p65)在过敏原刺激诱导16HBE细胞凋亡中的作用。结果过敏原刺激后使16HBE细胞内NF-κB(p65)m RNA和蛋白水平明显上调,明显诱导16HBE细胞凋亡和活化型caspase-3水平上调,沉默NF-κB可使过敏原刺激诱导的16HBE细胞凋亡率降低和活化型caspase-3水平上调减少。结论 NF-κB可介导哮喘过敏原刺激后的支气管上皮细胞凋亡。     

糖原合酶激酶-3β在肿瘤细胞中的分子作用机制

糖原合酶激酶-3β(glycogen synthase kinase-3β,GSK-3β)是一种多功能丝氨酸/苏氨酸激酶,通过磷酸化酪氨酸、丝氨酸和苏氨酸位点介导Wnt、Hedgehog、NF-κB和PI3K/Akt等信号通路,参与各类细胞功能的调节。GSK-3β在不同信号通路和细胞类型中扮演不同的角色,导致其在不同的恶性肿瘤中发挥促癌或抑癌的双重作用,与癌细胞的迁移和侵袭有直接关系。在胰腺癌和结肠癌研究中,GSK-3β的高表达调控通过相关信号通路,增强细胞增殖调控因子表达,抑制负性调控因子的活性,促进癌细胞的增殖。GSK-3β能激活上皮细胞间质转型过程中相关因子的表达,增强癌细胞扩散能力;相反,在胃癌和肺癌中,GSK-3β具有积极的抑癌作用。GSK-3β通过阻滞细胞周期和诱导细胞凋亡发挥抑癌作用,通过调节Wnt和PI3K/Akt信号通路,负向调控癌细胞的生长与侵袭,并且GSK-3β磷酸化相关因子以减弱其对癌细胞转移能力的刺激。本文总结了GSK-3β在不同恶性肿瘤中的作用及机制,并针对研究中存在的问题进行分析与展望,为相关领域的研究提供一定的理论基础。     

TNFα诱导激活NF-κB上调抑癌基因CDKN2B表达

NF-κB通过转录调控其靶基因,在肿瘤发生发展和精准治疗中起关键作用。过表达抑癌基因细胞周期蛋白依赖性激酶抑制剂2B（CDKN2B）可抑制肿瘤细胞增殖并诱导凋亡,但是否受NF-κB调节尚无报道。本文发现,NF-κB直接结合并上调CDKN2B基因：在TNFα处理的HeLa细胞内,CDKN2B的基因区覆盖大量NF-κB结合峰,其中富集倍数大于20的结合峰有14个。TRANSFAC软件分析发现,NF-κB结合峰内包含大量经典的κB位点。ChIP-qPCR证明,TNFα诱导NF-κB结合CDKN2B基因。将NF-κB结合峰中心区DNA片段插入荧光素酶报告基因载体中,发现该DNA片段的插入使荧光素酶相对活性上调至7.88倍,TNFα处理又使其相对活性提高到2.37倍,且NF-κB/p65 siRNA显著干扰其相对活性的升高。免疫荧光检测显示,TNFα诱导激活NF-κB进入细胞核,而NF-κB/p65 siRNA阻止它入核。此结果提示,我们成功构建了具有NF-κB转录活性差异的细胞模型,qPCR检测两个已知的NF-κB靶基因NFKB2和STAT5A的表达,进一步验证该细胞模型构建成功。利用此细胞模型,发现受TNFα诱导激活的NF-κB,能够上调CDKN2B基因。总之,本文发现抑癌基因CDKN2B是NF-κB新的靶基因,NF-κB直接结合并上调CDKN2B基因在转录水平的表达。本研究为抑癌基因CDKN2B的抗肿瘤应用奠定了基础。     

GSK-3 Represses Growth Factor-inducible Genes by Inhibiting NF-��B in Quiescent Cells

GSK-3 is active in the absence of growth factor stimulation and generally acts to induce apoptosis or inhibit cell proliferation. We previously identified a subset of growth factor-inducible genes that can also be induced in quiescent T98G cells solely by inhibition of GSK-3 in the absence of growth factor stimulation. Computational predictions verified by chromatin immunoprecipitation assays identified NF-κB binding sites in the upstream regions of 75% of the genes regulated by GSK-3. p50 bound to most of these sites in quiescent cells, and for one-third of the genes, binding of p65 to the predicted sites increased upon inhibition of GSK-3. The functional role of p65 in gene induction following inhibition of GSK-3 was demonstrated by RNA interference experiments. Furthermore, inhibition of GSK-3 in quiescent cells resulted in activation of IκB kinase, leading to phosphorylation and degradation of IκBα and nuclear translocation of p65 and p50. Taken together, these results indicate that the high levels of GSK-3 activity in quiescent cells repress gene expression by negatively regulating NF-κB through inhibition of IκB kinase. This inhibition of NF-κB is consistent with the role of GSK-3 in the induction of apoptosis or cell cycle arrest in cells deprived of growth factors.     

GSK-3β inhibition by lithium confers resistance to chemotherapy-induced apoptosis through the repression of CD95 (Fas/APO-1) expression

Lithium exerts neuroprotective actions that involve the inhibition of glycogen synthase kinase-3β (GSK-3β). Otherwise, recent studies suggest that sustained GSK-3β inhibition is a hallmark of tumorigenesis. In this context, the present study was undertaken to examine whether lithium modulated cancer cell sensitivity to apoptosis induced by chemotherapy agents. We observed that, in different human cancer cell lines, lithium significantly reduced etoposide- and camptothecin-induced apoptosis. In HepG2 cells, lithium repressed drug induction of CD95 expression and clustering at the cell surface as well as caspase-8 activation. Lithium acted through deregulation of GSK-3β signaling since (1) it provoked a rapid and sustained phosphorylation of GSK-3β on the inhibitory serine 9 residue; (2) the GSK-3β inhibitor SB-415286 mimicked lithium effects by repressing drug-induced apoptosis and CD95 membrane expression; and (3) lithium promoted the disruption of nuclear GSK-3β/p53 complexes. Moreover, the overexpression of an inactivated GSK-3β mutant counteracted the stimulatory effects of etoposide and camptothecin on a luciferase reporter plasmid driven by a p53-responsive sequence from the CD95 gene. In conclusion, we provide the first evidence that lithium confers resistance to apoptosis in cancer cells through GSK-3β inhibition and subsequent repression of CD95 gene expression. Our study also highlights the concerted action of GSK-3β and p53 on CD95 gene expression.     

异位（过）表达PGRN抑制IL-1β引起的髓核细胞损伤

炎症因子IL-1β是引起髓核细胞功能异常的关键因素之一。颗粒体蛋白原（progranulin,PGRN）是一种多功能生长因子,在组织修复、炎症反应等过程中发挥重要作用,但其在髓核细胞中的作用尚不清楚。本研究以IL-1β诱导的髓核细胞炎性损伤模型为研究对象,探讨PGRN对IL 1β诱导的髓核细胞损伤的保护作用及其机制。基因转染结合MTT方法证明,与IL-1β处理的细胞比较,过表达PGRN可逆转IL-1β引起的原代培养的髓核细胞生长抑制,促进细胞增殖。TUNEL技术和流式细胞分析显示,PGRN抑制IL-1β诱导的髓核细胞凋亡。Western印迹和RT-qPCR方法揭示,与IL-1β处理的细胞相比,过表达PGRN显著上调聚蛋白聚糖（aggrecan）和II型胶原（collagen type II）的蛋白质表达,但下调基质金属蛋白酶-13（MMP-13）、分解素-金属蛋白酶ADAMTS-5的表达,同时抑制IL-1β诱导的炎性因子IL-6、IL-8和TNF-α的表达,说明PGRN可缓解IL-1β引起的炎性反应,并减少细胞外基质（ECM）相关蛋白质的降解。此外,过表达PGRN还可降低p65、p-IkB a和β-catenin的蛋白质表达水平,提示PGRN可抑制IL-1β下游TNF-α介导的NF-κB信号途径及β-catenin途径。总之,上述结果提示,过表达PGRN可通过抑制IL-1β诱导的炎性反应、髓核细胞凋亡及基质代谢紊乱,缓解IL-1β诱导的髓核细胞损伤;PGRN的这种抗炎、抗基质降解作用可能与PGRN参与调控NF-κB和β-catenin信号途径有关。     

Progranulin promotes neurite outgrowth and neuronal differentiation by regulating GSK-3β

Progranulin (PGRN) has recently emerged as a key player in a subset of frontotemporal dementias (FTD). Numerous mutations in the progranulin gene have been identified in patients with familial or sporadic frontotemporal lobar degeneration (FTLD). In order to understand the molecular mechanisms by which PGRN deficiency leads to FTLD, we examined activity of PGRN in mouse cortical and hippocampal neurons and in human neuroblastoma SH-SY5Y cells. Treatment of mouse neurons with PGRN protein resulted in an increase in neurite outgrowth, supporting the role of PGRN as a neurotrophic factor. PGRN treatment stimulated phosphorylation of glycogen synthase kinase-3 beta (GSK-3β) in cultured neurons. Knockdown of PGRN in SH-SY5Y cells impaired retinoic acid induced differentiation and reduced the level of phosphorylated GSK-3β. PGRN knockdown cells were also more sensitized to staurosporine- induced apoptosis. These results reveal an important role of PGRN in neurite outgrowth and involvement of GSK-3β in mediating PGRN activity. Identification of GSK-3β activation as a downstream event for PGRN signaling provides a mechanistic explanation for PGRN activity in the nervous system. Our work also suggest that loss of axonal growth stimulation during neural injury repair or deficits in axonal repair may contribute to neuronal damage or axonal loss in FTLD associated with PGRN mutations. Finally, our study suggests that modulating GSK-3β or similar signaling events may provide therapeutic benefits for FTLD cases associated with PGRN mutations.     

GSK-3beta inhibition by lithium confers resistance to chemotherapy-induced apoptosis through the repression of CD95 (Fas/APO-1) expression

Lithium exerts neuroprotective actions that involve the inhibition of glycogen synthase kinase-3beta (GSK-3beta). Otherwise, recent studies suggest that sustained GSK-3beta inhibition is a hallmark of tumorigenesis. In this context, the present study was undertaken to examine whether lithium modulated cancer cell sensitivity to apoptosis induced by chemotherapy agents. We observed that, in different human cancer cell lines, lithium significantly reduced etoposide- and camptothecin-induced apoptosis. In HepG2 cells, lithium repressed drug induction of CD95 expression and clustering at the cell surface as well as caspase-8 activation. Lithium acted through deregulation of GSK-3beta signaling since (1) it provoked a rapid and sustained phosphorylation of GSK-3beta on the inhibitory serine 9 residue; (2) the GSK-3beta inhibitor SB-415286 mimicked lithium effects by repressing drug-induced apoptosis and CD95 membrane expression; and (3) lithium promoted the disruption of nuclear GSK-3beta/p53 complexes. Moreover, the overexpression of an inactivated GSK-3beta mutant counteracted the stimulatory effects of etoposide and camptothecin on a luciferase reporter plasmid driven by a p53-responsive sequence from the CD95 gene. In conclusion, we provide the first evidence that lithium confers resistance to apoptosis in cancer cells through GSK-3beta inhibition and subsequent repression of CD95 gene expression. Our study also highlights the concerted action of GSK-3beta and p53 on CD95 gene expression.