P21蛋白和XIAP在美伐他汀诱导A549细胞凋亡中的作用

目的 研究P21蛋白和凋亡相关基因XIAP在美伐他汀诱导A549细胞凋亡中的作用及其分子机制.方法 应用MTT法检测细胞系的增殖作用,流式细胞仪、透射电镜检测细胞周期和凋亡;用流式细胞术、Western blot和RT-PCR检测P21蛋白、XIAP蛋白及P21和XIAP mRNA的表达.结果 美伐他汀呈剂量和时间依赖性对A549增殖产生抑制;并诱导A549细胞G0/G1期阻滞和凋亡.美伐他汀对P21 mRNA及P21总蛋白的表达无影响,但可使P21胞膜蛋白的表达下降.美伐他汀作用后XIAP mRNA及XIAP蛋白的表达均下降.加入甲羟戊酸可完全逆转美伐他汀的上述作用.结论 美伐他汀通过甲羟戊酸途径抑制A549细胞增殖并诱导凋亡,使细胞周期进程阻滞于G0/G1期,XIAP参与美伐他汀诱导A549细胞凋亡的基因调控.美伐他汀靶向HMG-CoA还原酶,抑制P21蛋白异戊二烯化、阻止P21蛋白与细胞膜的结合,不影响P21总蛋白的表达.     

Aβ25-35对PC12细胞周期及P21、CDK4、E2F1、BAX基因表达的影响

目的 观察β-淀粉样肽25-35（Aβ25-35）对体外血清饥饿培养PC12细胞周期及 P21、CDK4、E2F1和BAX基因表达的影响。方法 用终浓度为25?mol/L Aβ25-35诱导PC12细胞,流式细胞仪分析细胞周期的改变与凋亡的关系;RT-PCR 和Western blot检测P21、CDK4、E2F1和BAX基因mRNA和蛋白表达。结果 PC12细胞血清饥饿培养24h约90%停滞于G0/G1期;25?mol/L Aβ25-35诱导PC12细胞8、16和24h与对照组比较,S期细胞百分率增加(P<0.01),16h后细胞凋亡率增加(P<0.01),可见亚二倍体凋亡峰(Ap峰);25?mol/L Aβ25-35诱导PC12细胞0~20h, P21 mRNA和P21 蛋白的表达下降;CDK4、E2F1、BAX mRNA和CDK4、BAX蛋白表达增高。结论 Aβ25-35可诱导同步化于G0/G1的PC12细胞重新进入细胞周期并随之出现凋亡,其机制可能与下调P21 mRNA和P21蛋白的表达,增加CDK4、E2F1、BAX mRNA和CDK4、BAX蛋白的表达有关。     

Mage-H1在PC12细胞分化前后的表达变化及其对细胞周期的影响

目的: 探讨黑色素瘤相关抗原H1(Mage-H1)在细胞增殖和分化调控中的作用。方法: 神经生长因子(nerve growth factor, NGF)诱导PC12细胞分化后用相差显微镜对其形态学进行观察。通过RT-PCR、Western blotting 检测分化前后Mage-H1表达变化情况。流式细胞技术分析PC12细胞瞬时表达Mage-H1对细胞周期的影响。结果: 经NGF诱导8 d后,92%以上PC12细胞属于已分化细胞。分化后的PC12细胞与对照组相比,Mage-H1表达上调。PC12细胞瞬时表达Mage-H1后被明显阻滞在G₀-G₁期。结论: Mage-H1可抑制PC12细胞增殖并促进细胞的分化。     

表没食子儿茶素没食子酸酯通过调控P53/miR-34a抑制鼻咽癌细胞的增殖

目的:观察表没食子儿茶素没食子酸酯(EGCG)对鼻咽癌细胞增殖的影响,并以微小RNA-34a(miR-34a)为靶点探讨其作用机制。方法:不同浓度的EGCG处理CNE-2Z细胞,CCK-8法、Ed U染色法和平板克隆形成实验检测细胞增殖能力的改变;流式细胞术检测细胞周期分布的改变;Western blot检测P53和Notch1蛋白水平的变化;real-time PCR检测miR-34a和Notch1 mRNA的表达。结果:EGCG处理后,CNE-2Z细胞的增殖受到明显抑制,克隆形成能力降低,细胞周期阻滞于G0/G1期,呈剂量依赖关系;随着EGCG浓度增高,P53和miR-34a的表达水平明显上调,而其下游Notch1 mRNA和蛋白的表达水平则明显下降。结论:EGCG可能通过调控P53/miR-34a/Notch1通路诱导细胞周期阻滞,抑制鼻咽癌细胞增殖。     

P53与癫痫神经元损伤

细胞凋亡是当前生命科学研究的热门领域之一,全球自然科学研究论文最集中三个领域分别是细胞信号传导,细胞凋亡和基因组研究。随着对细胞凋亡领域的深入研究,许多机制正逐步阐明,并发现了许多重要的信号分子,使信号分子在细胞凋亡中的地位越来越引人关注。P53蛋白是一个肿瘤抑制蛋白,在组织中广泛表达,通过影响编码细胞周期相关蛋白的基因表达来调控细胞周期的G1期停滞并诱导细胞凋亡,近年来研究认为P53蛋白在细胞周期调控,基因组稳定性维持,细胞凋亡及细胞分化中起重要作用。1 P53蛋白结构与家族成员分类P53基因位于人类染色体17q13.1,含…     

单胺氧化酶抑制剂诱导胶质瘤细胞的体外分化

为研究单胺氧化酶抑制剂(TCP)对体外培养的人脑胶质瘤U251细胞的诱导分化作用,以不同浓度TCP单独或与100nmol/L组蛋白去乙酰化酶抑制剂(TSA)联合处理U251细胞。采用倒置显微镜观察细胞形态学变化;噻唑蓝(MTT)比色法检测细胞增殖变化;流式细胞仪检测细胞周期变化;Hoechst 33258染色显示细胞凋亡;Real-time PCR和Western印迹法检测分化相关基因mRNA和蛋白表达水平的改变。结果表明:TCP可诱导细胞突起增多且变细长,抑制细胞增殖,阻滞细胞周期于G1期,抑制全能性转录因子Oct4和Sox2的表达,上调分化标志基因胶质纤维酸性蛋白(GFAP)的表达,TCP联合TSA也诱导了GFAP的高表达。这些结果提示:TCP可诱导胶质瘤U251细胞分化,TSA对TCP诱导细胞分化有协同作用。     

NGF和GDNF基因重组逆转录病毒体外感染神经干细胞及其鉴定

目的 探讨神经干细胞（NSC）直接作为基因靶细胞能否被重组逆转录病毒感染以及感染后目的基因的表达。方法 分别用NGF和GDNF基因重组逆转录病毒上清液感染NSC2d;G418筛选后加入bFGF扩增培养;取感染后的NSC培养液（NGF／GDNF条件培养液）培养PC12细胞和中脑腹侧神经元;用免疫组织化学染色方法检测中脑腹侧多巴胺神经元的形态改变以及感染后NSC对目的基因的表达。结果 经G418筛选后,约50％感染NGF和GDNF基因重组逆转录病毒的NSC呈G418抗性;这些感染后的NSC开始分化,分裂球向四周长出放射状突起,部分细胞沿突起向外迁移生长;感染NGF基因的NSC呈星形,胞体较大,突起较粗,感染GDNF基因的NSC呈梭形,胞体较小,突起较长。经NGF条件培养液培养的PC12细胞,数量增多,突起明显变长。经GDNF条件培养液培养的中脑多巴胺神经元（TH阳性细胞）其胞体亦增大,突起伸长。大部分G418抗性的NSC出现NGF和GDNF免疫染色。结论 神经干细胞可直接作为基因靶细胞,能被NGF和GDNF基因重组逆转录病毒有效感染而表达和分泌有生物学活性的NGF和GDNF。     

微注射抗ra■P21抗体抑制生长因子诱导的PC12细胞分化

ras细胞原癌基因产物P21可能在受体-配件诱导的细胞分化中发挥信号传导作用。本文作者利用了融合的嗜铬细胞瘤细胞(PCl_2),这种细胞和非融合细胞一样在神经生长因子(NGF)作用下可产生一些交感神经的表型特征,包括细胞分裂停止和长出突起等。细胞在NGF处理前微注射抗ras     

红景天苷对小鼠MSCs的增殖及其细胞周期的影响

目的本研究探讨了不同浓度红景天苷通过ERK信号通路对小鼠骨髓间充质干细胞增殖和细胞周期变化的影响及机制。方法实验分为对照组(D-MEM/F-12完全培养液)、不同浓度红景天苷(5~100μg/m L)诱导组和阻断组(5~100μg/m L+30μg/L PD98059),利用CCK8法、流式细胞术及Western blot分别检测ERK信号通路阻断前后细胞抑制率、细胞周期及其相关蛋白的表达。结果 10μg/m L诱导组和阻断组均能抑制细胞增殖,且5μg/m L(P0.01)、25μg/m L(P0.05)和100μg/m L(P0.05)诱导组对细胞抑制显著高于阻断组。25μg/m L诱导组和阻断组G_0/G_1期细胞比例均增加,细胞周期阻滞于G0/G1期。诱导组和阻断组cyclin A和cyclin D1蛋白的表达与对照组比较均下调,P21蛋白的表达上调。阻断组cyclin A蛋白的表达与诱导组比较明显下调(P0.01);50和100μg/m L诱导组与阻断组相比cyclin D1蛋白表达显著下调,P21蛋白的表达显著上调(P0.01)。结论红景天苷能通过调节细胞周期相关蛋白的表达抑制小鼠MSCs细胞的增殖和细胞周期的改变。     

p27~(Kip1)调控永生化人神经前体细胞分化的机制

目的研究p27Kip1在永生化人神经前体细胞分化中的作用,探讨神经前体细胞的分化机制。方法取本课题组已建立的永生化人神经前体细胞系hSN12W-TERT细胞(第12代)进行培养,在细胞进入对数生长期时给予1μmol/L全反式视黄酸(RA)诱导,重复诱导3次,每次均在诱导的第3、5、7天收集细胞,用流式细胞仪分析RA诱导第3天细胞周期的变化,用免疫印迹法检测RA诱导第3、5、7天p27Kip1、p21cip1细胞周期蛋白依赖激酶2(cdk2)及S期激酶相关蛋白2(skp2)的变化。结果流式细胞术结果显示,hSN12W-TERT细胞经1μmol/LRA诱导3d后,G0/G1期细胞的比例由77.25%上升至85.68%,而S期的比例由9.38%下降到8.57%。免疫印迹法结果显示,RA诱导第3天,hSN12W-TERT细胞p27Kip1蛋白表达比未经RA诱导的细胞增加,并在RA诱导第5天达到高峰(P0.05)。未经RA诱导的正常hSN12W-TERT细胞p21Cip1蛋白表达弱,RA诱导后p21Cip1蛋白的表达略呈下降趋势。RA诱导前后hSN12W-TERT细胞cdk2蛋白的表达变化不明显,但反映cdk2活性的磷酸化cdk2(p-cdk2)的表达在RA诱导后明显下降,同时,参与p27Kip1泛素降解途径的重要因子skp2的表达在RA诱导后明显下降。结论在RA诱导hSN12W-TERT细胞分化的过程中,p27Kip1通过抑制cdk2的活性而发挥促细胞分化的作用,且RA诱导后p27Kip1蛋白含量增加与其泛素降解途径被抑制密切相关。     

Genistein enhances the NGF-induced neurite outgrowth

In the present report, we studied if an isoflavone, genistein, enhances the nerve growth factor (NGF)-induced neurite outgrowth of PC12 cells. Application of genistein enhanced the NGF-induced neurite outgrowth. Knockdown of Na+/K+/2Cl- cotransporter isoform 1 (NKCC1) abolished the stimulatory effect of genistein on the neurite outgrowth. These observations indicate that NKCC1 is essential for genistein to stimulate the NGF-induced neurite outgrowth, although genistein had no effect on the protein expression of NKCC1. On the other hand, genistein activates NKCC1 as shown in our previous study. Taken together, these observations indicate that genistein enhanced the NGF-induced neurite outgrowth in PC12 cells via activation of NKCC1.     

Inhibition of NGF-induced neurite outgrowth of rat pheochromocytoma cells (PC12) following administration of dioxyamphetamine

Amphetamine analogs are known to induce not only neurotoxicity at serotonergic axon terminals but also neocortical neuronal degeneration. However, a much less studied aspect involves the impact of amphetamine exposure on neuronal development. The present study investigated whether pretreatment of PC12 cells with dioxyamphetamine (DA) alters differentiation of PC12 cells by NGF and, if so, which components of the Ras/Raf/MEK/ERK pathway known to be involved in the differentiation response to NGF are particularly affected. Though exposure of PC12 cells to DA 1 h prior to NGF treatment resulted in apopotosis, several PC12 cells survived. However, neurite outgrowth of these NGF-responsive cells was repressed. Immunoblots of whole cell extracts revealed a strong induction rather than inhibition of ERK phosphorylation up to 48 h after DA/NGF treatment. Our results indicate that NGF-mediated neurite outgrowth was inhibited by pretreatment with DA, and this blockage of NGF-induced neuritogenesis was not due to an inhibition of ERK phosphorylation.     

Voltage dependent calcium currents in PC12 growth cones and cells during NGF-induced cell growth

The role of calcium currents in the regulation of neurite outgrowth is still rather speculative. As a contribution to this field, macroscopic voltage dependent calcium currents were investigated in relation to the nerve growth factor (NGF)-induced outgrowth of neurites in PC 12 cells. Calcium currents were recorded in isolated growth cones of PC 12 cells using the whole cell patch clamp method. The currents were activated at high voltages and only slightly inactivated with time. The currents were identical to those found in the cell soma of PC 12 cells and similar to the classical high-voltage-activated calcium current found in many neuronal cells. The peak current density in the growth cones was in the same range as in the cell somata. The calcium currents of the cell somata were not modified during the early phase of NGF application, despite the occurrence of NGF-induced soma growth and outgrowth of neurites. The current density at this time was therefore lower in NGF-treated cells than in untreated cells. In a later phase, maximal current amplitudes of NGF-treated cells were higher than in untreated cells indicating an increase in current density to values similar to that found in the untreated cells. In addition, the calcium current inactivation was found to be more pronounced in the NGF-treated cells by that time. The results are discussed with regard to a possible role of calcium currents in the regulation of NGF-induced neurite outgrowth in these cells.     

Involvement of P2Y13 receptor in suppression of neuronal differentiation

We examined the receptor-mediated effects of extracellular ATP on neuronal differentiation of PC12 cells, Neuro2a cells and MEB5 cells by using a series of receptor antagonists. The P2Y13 receptor antagonist MRS2211 significantly accelerated neurite outgrowth in all cases. Treatment with nerve growth factor (NGF) alone activated ERK1/2 in PC12 cells, and the activation was further increased by MRS2211. These results suggest involvement of P2Y13 receptor in suppression of neuronal differentiation. Thus, P2Y13 receptor antagonists might be candidates for treatment of neurodegenerative diseases.     

ERK在NGF诱导PC12 细胞分化中的作用

目的探讨细胞外信号调节激酶(ERK)在NGF。诱导的PC12细胞分化中的作用机制。方法以NGF处理PC12细胞建立分化模型,运用免疫印迹检测不同浓度不同作用时间时NGF对ERK1／2蛋白和磷酸化ERK1／2蛋白水平的影响,并观察MAPK／ERK激酶(MEK)抑制剂U0126对NGF诱导的细胞形态学改变的影响。结果ERK1／2蛋白的磷酸化呈现NGF剂量和时间依赖性。NGF作用细胞5min即可观察到明显的ERK1／2蛋白磷酸化,持续1h左右,2h时降低到初始水平,而细胞形态的改变出现在NCF作用12h以后。倒置相差显微镜观察可见PC12细胞分化的程度与ERK1／2活化持续的时间正相关,U0126可完全即时抑制ERK1／2的活化,而ERK1／2活化的抑制可完全阻断。NGF诱导的PC12细胞分化。结论ERK1／2的活化是PC12细胞发生分化的必需事件,其活化时间的长短对分化具有决定作用。     

A synthetic analog of verbenachalcone potentiates NGF-induced neurite outgrowth and enhances cell survival in neuronal cell models

This study uses NeuroScreen-1 (NS-1) cells, a derivative of pheochromocytoma (PC12) cells, to examine neurite outgrowth induced by a novel synthetic verbenachalcone derivative, DSRB20-022 (C22). We treated NS-1 cells with varying concentrations of C22 in the presence of 2 ng/mL nerve growth factor (NGF). A dose-dependent effect of C22 was observed at concentrations of 2 μM and above, resulting in significant enhancement of NGF-dependent neurite outgrowth in NS-1 cells. C22 did not exhibit neuritogenic activity in the absence of NGF, but promoted a concentration-dependent increase in neurite-bearing cells without inducing cytotoxicity. Cell viability assays showed that C22 and the parent compound verbenachalcone (VC) are neuroprotective and enhanced survival of NS-1, PC12, and the murine neuro-2A (N2a) cell lines under conditions of serum deprivation. The results show that augmentation of NGF-induced neurite outgrowth by C22 in NS-1 was dependent on MAP kinase. Furthermore, the neuroprotective function of C22 and VC was accompanied by suppression of caspase-3/7 activation. However, C22 and VC exerted their antagonistic effects on caspase-3/7 activation through potentially different mechanisms of action.     

Functional role of JNK in neuritogenesis of PC12-N1 cells

JNKs, also known as SAPKs, are activated in response to a wide variety of factors including growth factors, cytokines, UV radiation, and heat shock. In the rat pheochromocytoma PC12 cells, the JNK signaling pathway mediates diverse functions such as differentiation and apoptosis. We have previously shown that activated JNK is required for later stages of neuritogeneis induced by NGF in a variant PC12 cell line (N1). Here, the functional role of JNK in N1 cells is further investigated. We show that NGF treatment, which induces extensive neurite branching and cell soma enlargement in the N1 cells, stimulates a biphasic activation of JNK. The first phase of activation is rapid and transient, beginning at 15 min after NGF exposure and lasting approximately 45 min. The second phase of activation is sustained, beginning at 9-12 h of NGF treatment and lasting for at least 24 h. Similar biphasic pattern of JNK activation is also observed in the parental PC12 cells. Using the specific JNK inhibitor SP600125, we show that the biphasic activation is necessary for neurite outgrowth and branching, and that inhibition of either phase suppresses neuritogenesis in the N1 cells. These results suggest that dynamic JNK activation may play a key role in neurite outgrowth during neuronal development.     

Differences in neuritogenic response to nitric oxide in PC12 and PC12h cells

We have demonstrated that a natural iridoid compound, genipin, induces neurite outgrowth through the nitric oxide (NO)-cGMP-protein kinase G signaling pathway in PC12h cells. PC12 cells, the parental cell line of PC12h cells, have been shown to carry out neurite extension that accompanies NO production in response to nerve growth factor (NGF). This neurite outgrowth was significantly inhibited by NG-nitro-L-arginine methyl ester (L-NAME), an NO synthase inhibitor, in both PC12 and PC12h cells, suggesting that the neuritogenesis is NO-dependent in both cells. In this report, we investigated whether genipin also induces neurite outgrowth in PC12 cells in order to determine the NO-dependent neurotrophic action of genipin in more than just one cell type. Genipin induced marked neurite outgrowth in PC12h cells but not in PC12 cells. The genipin-induced neurite outgrowth was significantly inhibited by L-NAME in PC12h cells. An NO donor, NOR4, also significantly induced neurite outgrowth in a concentration-dependent manner in PC12h cells but not in PC12 cells. On the other hand, NGF-primed PC12 cells exhibited significant neurite extension, which was inhibited by L-NAME, in response to genipin. Interestingly, NGF-primed PC12 cells responded to NOR4 extending neurites and expressed detectable neuronal NO synthase protein which is not detected in naive PC12 cells. These results suggest that genipin exerts a neuritogenic action on neuronal cells which are responsive to NO itself. Furthermore, the results also suggest that PC12h cells are more suitable for the study of NO-dependent neuronal function than PC12 cells which were not responsive to NO.     

Neurite outgrowth of PC12 mutant cells induced by orange oil and d-limonene via the p38 MAPK pathway

We studied the effects of natural essential oil on neurite outgrowth in PC12m3 neuronal cells to elucidate the mechanism underlying the action of the oils used in aromatherapy. Neurite outgrowth can be induced by nerve growth factor (NGF), where ERK and p38 MAPK among MAPK pathways play important roles in activating intracellular signal transduction. In this study, we investigated whether d-limonene, the major component of essential oils from oranges, can promote neurite outgrowth in PC12m3 cells, in which neurite outgrowth can be induced by various physical stimulations. We also examined by which pathways, the ERK, p38 MAPK or JNK pathway, d-limonene acts on PC12m3 cells. Our results showed that neurite outgrowth can be induced when the cells are treated with d-limonene. After treatment with d-limonene, we observed that p38 MAPK is strongly activated in PC12m3 cells, while ERK is weakly activated. In contrast, JNK shows little activity. A study using an inhibitor of p38 MAPK revealed that neurite outgrowth in PC12m3 cells is induced via the activation of p38 MAPK by d-limonene. The results thus indicate that d-limonene may promote neural cell differentiation mainly via activation of the p38 MAPK pathway.